Logical Observation Identifier Names and Codes (LOINCÔ)

Description File Name

LOINC database (WP 6.0) uncompressed LOINDBW1.WP6

LOINC database (WP 6.0) PKZIPped LOINDBW1.ZIP

LOINC database (WinWord 2.0) uncompressed LOINDBWW.DOC

LOINC database (WinWord 2.0) PKZIPped LOINDBWW.ZIP

LOINC database (ASCII) uncompressed LOINDBT1.TXT

LOINC database (ASCII) PKZIPped LOINDBT1.ZIP

LOINC database (DBF) self-extracting LOINCDBF.EXE

LOINC Users' Guidel (WP 6.0) LOINMAN1.WP6

LOINC Users' Guide (WinWord 2.0) LOINMAN1.DOC

LOINC Introduction (ASCII) LOININTR.TXT

LOINC Read Me (ASCII) LOINRDME.TXT

LOINC Release Notes (ASCII) RELNOTES.TXT

Copyright and Terms of Use

Copyright 1995 Regenstrief Institute and the Logical Observation Identifier Names and Codes (LOINC&tm;) Committee. All rights reserved.

Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, or distribute the LOINC codes, LOINC Users' Guide, and the contents of the LOINC database for any purpose, so long as this copyright notice appears on any copies of the LOINC database and Users' Guide, and that the following conditions are met.

Users of the LOINC codes agree to the following conditions:

1) They will not change the meanings of any of the LOINC codes.

2) They will not change any contents in the defined LOINC Fields. (Users may add their own new fields to the database if they want to attach additional information to the existing LOINC record.)

3) They will include this notice of copyright and terms of use in any copies of the LOINC database that they distribute.

4) If new records are added to the LOINC database as distributed to deal with local requirements, these records must be assigned a LOINC code containing a leading alphabetic "X" so that the new term cannot be confused with new LOINC codes as they are assigned by the LOINC committee.

5) Those who incorporate any part of the LOINC database into another laboratory test definition database for distribution outside of their corporation must include the LOINC code (field #1) all six name fields (#2-7), the related terms (field #8), and the answer list (field #18), and include this copyright notice on the electronic document that incorporates the LOINC database.

Regenstrief Institute and the members of the LOINC Consortium do not accept liability for any omissions or errors in the LOINC database, and all EXPRESS AND IMPLIED WARRANTIES, INCLUDING THOSE RELATING TO MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

LOINC is a trademark of the Regenstrief Institute. This legend should be displayed on every copy of the database (both on the diskette itself and in a text file loaded onto the diskette or onto the Internet), and on all user manuals and other materials used in connection with the LOINC database. Acknowledgements

We wish to thank Henrik Olesen, Chairman of IUPAC, Commission on Quantities & Units in Clinical Chemistry, for his very helpful comments and insights about laboratory test coding.

This endeavor was supported in part by grants and contracts from the John A. Hartford Foundation of New York, the National Library of Medicine (Contract NO1-LM-3-3410), and the Agency for Health Care Policy and Research (AHCPR) (Grants HS 05626 and HS 07719-013). Much of the work was performed under the auspices of the Regenstrief Institute.

Preface and Introduction

The LOINC database provides a set of universal names and ID codes for identifying laboratory test results. The purpose is to facilitate the exchange and pooling of clinical laboratory results, such as blood hemoglobin or serum potassium, for clinical care, outcomes management, and research. Currently, many laboratories are using ASTM 1238-94 or its sister standard, HL7, to send laboratory results electronically from producer laboratories to clinical care systems in hospitals. Most laboratories identify tests in these messages by means of their internal (and idiosyncratic) code values. So the receiving medical informatics systems cannot fully "understand" the results they receive unless they either adopt the producer's laboratory codes (which is impossible if they receive results from multiple source laboratories, e.g.; the hospital lab, the local commercial lab, and a nursing home lab), or invest in work to map each laboratory's code system to their internal code system.[1]

If laboratories all used the LOINC codes to identify their results in data transmissions, this problem would disappear. The receiving system with LOINC codes in its master vocabulary file would be able to understand and properly file HL7 results messages that also use the LOINC code. Similarly, government agencies would be able to pool results (within limits) for tests from many sites if they were reported electronically using the LOINC codes. The LOINC codes (and names) for test observations should be of interest to hospitals, clinical laboratories, doctors' offices, state health departments, governmental health care providers, third-party payers, and organizations responsible for quality assurance and utilization review.

The LOINC codes are not intended to transmit all possible information about a test. They are only intended to identify the test result. Other fields in the message can transmit the identity of the source laboratory and very detailed information about the sample. (For instance, the result code may identify a blood culture, but the message source code can be more specific and identify the sample as pump blood.) The level of detail in the LOINC definitions was intended to distinguish tests that are usually distinguished as separate test results within the master file of existing laboratory systems. Indeed, we are using the master files from seven U.S. laboratories to shape this effort.

Each LOINC record corresponds to a single test result. (The LOINC database does not yet deal with orderable sets of tests such as CHEM 12.) The record includes fields for specifying:

1) Component (analyte) , e.g., potassium, hemoglobin, hepatitis C antigen.

2) Property measured , e.g., a mass concentration, enzyme activity (catalytic rate).

3) Whether the measurement is a momentary observation at a point in time, or an observation integrated over time , e.g., 24-hour urine.

4) The type of sample , e.g., urine, blood.

5) The type of scale , e.g., whether the measurement is quantitative (a true measurement) or nominal (red, blue, green).

6) Where relevant, the method used to produce the result or other observation.

It also contains information about the amount, route, and timing of physiologic or pharmacologic challenges (e.g., oral glucose tolerance test, which would be expressed in LOINC as GLOCOSE^1H POST 100 DL GLUCOSE PO[2]) The LOINC identifiers do not usually include the method in the name for chemistry tests, where tests are more often standardized to normalized methods, but do include it for most serological tests and coagulation studies. This same distinction is usually reflected in the master files of existing laboratories. Of course, the method can be reported as a separate item of information in a result message regardless of whether it is part of the test name.

We have used many sources for constructing the database, including the Silver Book from the International Union of Pure and Applied Chemistry (IUPAC) and the International Federation of Clinical Chemistry (IFCC),[3] textbooks of clinical pathology (e.g. Henry[4] and Tietz[5]), the expertise and work of the LOINC members, and Euclides. We have also reviewed the master test files of seven sources (Indiana University/Regenstrief, University of Utah, Association of Regional and University Pathologists (ARUP), Mayo Medical Laboratories, LDS Hospital in Salt Lake City, the Department of Veterans Affairs, Corning Medical Informatics, and University of Washington). This has been an empirical effort. Our goal is to provide codes to which laboratories could map to their master files.

The database includes fields for each of the six parts of the name, and often also includes Euclides codes (for the component/analytic part of the name), IUPAC/IFCC codes, and ASTM codes, as well as related words, synonyms, and comments. We plan to map the LOINC code to SNOMED and other code synonyms as well. Related words ("synonyms") are included to facilitate searches for individual laboratory test and clinical observation results.

Laboratories and managers of medical records systems should record the LOINC codes as attributes of their existing test/observation master files and use the LOINC codes and names in the OBSERVATION ID field of the ASTM and HL7 OBX segment and the corresponding CEN TC251 messages to identify laboratory results.

The LOINC database is presented to you as an electronic document grouped by "sensible" categories to make it easier to find general areas of interest. We have the usual categories of chemistry, hematology, serology, microbiology, and toxicology; we also have categories for drugs and the cell counts you would find reported on a complete blood count or a cerebrospinal fluid cell count. We have separated antibiotic susceptibilities into their own category. We have a small category for virology that include methods for identifying viruses (isolated and antigen), and also one called clinical where we collect observations that come from the requestor but are reported back by the laboratory (e.g. inspired oxygen). Table 16 lists all of these classes in detail. There is nothing sacred about these categories. You will be able to sort the database by whatever class is convenient for your application when you get the electronic version.

We are aware of gaps and areas that are not complete. For example, we have not yet included content for surgical pathology or cytology. (These should be covered within the next four to six months.) We have only included observation names with unspecified (XXX) samples for common laboratory chemistry tests; more may be needed. A few hematology records as yet have no kind of property. We have only addressed individual results, not orders for tests that return more than one result. In a few cases, we have suggested standard answer lists for tests whose results are usually reported as codes. We have defined fields in the database for a number of data elements, e.g., typical units, sample normal ranges, but most of those fields are not filled in. We hope to enrich the existing lists of synonym and answers in the next version.

For some kind of tests and observations, the database provides several ways to report values. For example, blood cell antigens might be presented as a "panel" with separate "tests" which report each possible antigen as present or absent if the test is to establish paternity; for crossmatching, the result would be reported as a list of antigens found. We try to provide for both methods of reporting in the LOINC database by including codes for both types of test identifiers.

The Regenstrief Institute and the LOINC committee will maintain the database while grant support is available (at least until October 1997). We expect to find a long-term home for the database before then. The LOINC database (which identifies over 6300 different lab tests and clinical observations) and supporting documentation will be available through the Duke HL7 standards data list server. Anonymous FTP and Gopher access is available at dumccss.mc.duke.edu. The directory is standards/HL7/ termcode/loinclab. The World Wide Web URL is http://dumccss.mc.duke.edu/ ftp/standards/HL7/termcode/loinclab/.

The LOINC database is stored in six file formats. In each of them, the first part of the file contains the copyright notice with permission to use the database for any purpose without charge or written permission. We have copyrighted the database and this document to assure that multiple variants of the codes do not emerge. Having many variants would defeat the purpose of a universal identifiers for test results.

Tab Delimited ASCII: Each record of the database is on a separate line. Each record is terminated by CR/LF, and each field is delimited by a tab character. Fields are enclosed in double quotes ("). Spreadsheet and database programs can easily handle such files, but a word processing document in this format would be awkward. The ASCII file is the "database of record" -- unlike the word processing versions, it will always contain all implemented fields.

WordPerfect 6.0 file: This file is formatted to print landscape in a Courier 6 point font. Some of the longer fields float vertically. This will result in an easily read document, but it is useless for input into databases or spreadsheets. The dimensions of the printed page make it impossible to display all database fields in this file.

WinWord 2.0 file: This file was produced by writing out the WordPerfect file through the WinWord export filter. It has been loaded into WinWord and examined; the translation is usable but not perfect. If your system does not contain the fonts used in the original file, the columns may be misaligned. Consult the Word for Windows Help topic "Improving compatibility with a document created in a different file format" for hints on dealing with this. Import of this file into Word for DOS has not been tested.

Each of these files is available either zipped and unzipped. (PKUNZIP v. 2.04 or compatible required)

The LOINC database is also available as a dBase (DBF) file. This database, with accompanying index and documentation, is available as a self-extracting ZIP file LOINCDBF.EXE. The database and index were created using Microsoft FoxPro&tm; 2.5.

The LOINC Users' Guide is also available both as a WordPerfect 6.0 file or a WinWord 2.0 file. This Users' Guide explains the structure of the database, its rationale, and the rules we used for naming test results. It is not compressed. The Winword file, like the WinWord database file described above, was created with the WordPerfect export filter, and like the database file, it is usable but not perfect. In particular, table of contents tags are replaced with "ERROR: BOOKMARK NOT FOUND" and the automatically generated section numbers are incorrect. Tables are sometimes misaligned but are still readable. See the preceeding paragraph for font translation information. Import of this file into Word for DOS has not been tested.

The introduction to the Users' Guide is available as a separate ASCII text file.

We welcome corrections or extensions to the database. We are not interested in adding terms that might be needed in some future situation but we are interested in adding test observations that are actively being reported today. If you wish to submit terms that are not yet included, please put terms in the LOINC format as described in this guide and exemplified in the LOINC database. Please include a letter describing your role in laboratory computerization, the planned use for these terms, and your mailing and email address. (If you submit more than 10 terms, please submit them as ASCII documents, one term per line and tab delimited, or as a DBASE file). Fewer than ten terms may be submitted on hard copy. If you have a big submission in mind, it would be best to contact one of the LOINC committee members to discuss the project and to submit a trial set before you embark on the full project. For the test name-field, you must always complete at least the first (name), third (time aspect), fourth (specimen), and fifth (type of scale) parts of the name. We will help with the second part of the name (kind of property). You must also include synonyms and a description of the variable. Become completely familiar with the LOINC database, so you can be sure the term(s) of interest is not already included, and use the LOINC Users' Guide to build the entry for each of the specified fields.

Table 1

Description	File Name
LOINC database WP 6.0 uncompressed	LOINDBW1.WP6
LOINC database WordPerfect 6.0 PKZipped	LOINDBW1.ZIP
LOINC database WinWord 2.0 uncompressed	LOINDBW1.DOC
LOINC database WinWord 2.0 PKZipped	LOINDBWW.ZIP
LOINC database ASCII file uncompressed	LOINCDBT1.TXT
LOINC database ASCII file PKZipped	LOINCDBT1.ZIP
LOINC database DBF files self-extracting	LOINCDBF.EXE
LOINC Users' Guide WP6.0	LOINMAN1.WP6
LOINC Users; Guide WinWord 2.0	LOINMAN1.DOC
LOINC introduction ASCII	LOININTR.TXT
LOINC Read Me ASCII	LOINRDME.TXT
LOINC Release Notes	RELNOTES.TXT

We are expanding the scope of this effort to other clinical variables (such as hospital measurements, including: vital signs, CNS pressure monitoring, intake and output, electrocardiograph measurements, obstetric ultrasound measurements).

When writing, provide a description of your background and interest. Mail correspondence to:

Regenstrief Institute for Healthcare

c/o Kathy Hutchins

1001 W. 10th St. RG-5

Indianapolis, IN, 46202

Internet: loinc@regenstrief.iupui.edu.

Release Notes

Version 1.0g

Released 4/28/96

Approximately 100 new terms added in a variety of areas. Drug terms linked to MediSpan 10-digit GPI codes where available in new field GPI_CD. Drugs with multiple GPI entries are linked in GPI_CD_TOTAL. New field REFERENCE contains references to textbook, journal, or other source

which provided information about term.

Beginning with Version 1.0g, LOINC is available in DBF format. This format is distributed as LOINCDBF.EXE, a self-extracting file containing the DBF, accompanying CDX, and a read.me file.

Version 1.0f

Released 12/21/95

Classes VIRO, PROBE, BACT, and SERO terms for infections agents reclassifed as MICRO (microbiology). Approximately XXX new microbiology terms added. Corrections to properties, IUPACcodes, and EUCLIDES codes. Link to Metpath codes corrected. Word and WordPerfect versions of database rearranged to show Metpath code links and make identification of deleted terms

easier. Variable order changed in tab-delimited database. Changes documented in new release of Users' Guide.

Version 1.0e

Released 09/15/95

About 25 corrections to properties to correspond to IUPAC usage. Term 6300-8 added for glucose in amniotic fluid. Nomenclature of parts of name changed to conform more closely to IUPAC: measure = component/analyte; timing = time aspect; specimen = system/sample; precision = scale.

Version 1.0d

Released 7/14/95

Approximately 350 terms added: allergen IGE tests (these are often called RAST tests, after the commonly used method, but more than one method is used) and coagulation tests -- mostly

beginning with the letters P through Z -- which which were inadvertently omitted from Release 1.0a.

We have established links between LOINC codes and approximately 1500 Metpath codes. These are mapped in METPATH_CODE.

In most instances, we have supplied properties for the records whose property fields were blank. Most of these terms are in the hematology class.

We identified a number of duplicate entries. Usually these had quite different names but the names were synonyms. In these cases, one of the duplicates was marked "DEL" in the STATUS

field, and the MAP_TO field of that record contains a pointer to the correct record. In every case the LOINC record with the smaller LOINC number was identified as the preferred LOINC record

and the other one was marked as a "deleted term." (Records are never actually deleted from the LOINC database, but if a term should no longer be used, the value of STATUS will be set to

DEL.)

Version 1.0c

Released 6/28/95

Two terms with duplicate LOINC Number 5917-0 marked Status="DEL" and reassigned to LOINC Numbers 5932-9 and 5933-7.

Version 1.0b

Released 6/23/95

Approximately 20 Chemistry terms added.

Version 1.0a

Released 5/24/95

"MAP_TO" field added to provide mapping to new terms when old terms are marked for logical deletion (we put a "DEL" in the STATUS field to indicate this.) We added 16 coagulation terms to

the WP version; these terms were in the 1.0 release of the ASCII database but were mistakenly omitted from the WordPerfect 1.0 release. We marked term 3173-2 (Activated Partial Thromboplastin

Time) as STATUS="DEL" because it was a duplicate of term 5898-2 (Coagulation Surface Induced, which carries APTT and Activated Partial Thromboplastin Time as synonyms).

In BC (blood count) terms, METHOD=FLOW CYTOMETER changed to METHOD=AUTOMATED COUNT to more accurately reflect lab terminology.

Version 1.0

Released 4/24/95LOINC COMMITTEE MEMBERS

Clem McDonald, M.D., Chairman and Editor

Regenstrief Institute

Indiana University School of Medicine

Indianapolis, IN

Email: loinc@regenstrief.iupui.edu

John Baenziger, M.D.

Indiana University Hospital

Indianapolis, IN

Email c/o: rgotten@indymed.iupui.edu

Linda Charles, Ph.D.

Quintiles, Inc.

Morrisville, NC

Email: lcharles@quintiles.com

Georges DeMoor, M.D.

University Hospital Ghent

Ghent, Belgium

Email: georges.demoor@rug.ac.be

Diane Dwyer

Maryland Dept. of Health & Mental Hygiene

Baltimore, Maryland

Email:dmd0@wonder.em.cdc.gov

Tom Fiers, M.D.

University Hospital Ghent

Ghent, Belgium

Arden Forrey, Ph.D.

University of Washington

Seattle, WA

Email:forraw@u.washington.edu

Brian Griffin

Corning Medical Informatics

Rutherford, NJ

Email: griffinbr@aol.com

Stan Huff, M.D.

IHC/Primary Children's Medical Ctr.

Salt Lake City, UT

Email: smhuff@cc.utah.edu Dennis Leavelle, M.D.

Mayo Medical Laboratories

Rochester, MN 55901

Email: dleavelle@mayo.edu

Diane Leland, Ph.D.

Riley Hospital for Children

Department of Medicine -- Pathology

I.U. Medical Center

Indianapolis, IN

Doug Martin, M.D.

Roudebush VAMC

Indianapolis, IN

Email: doug@hsrd.iupui.edu

Frank Stalling, M.D.

Dallas ISC

Dept. of Veterans Affairs

Grand Prairie, TX

Email: stalling.frank@forum.va.gov

Anders Thurin

University Hospital

Linkoping, Sweden

Email: andth@klinfys.liu.se

Wayne Tracy

SpaceLabs Medical, Inc.

Overland Park, KS

Email: wrtracy@wrt.win.net

Ann Tullis

Indiana University Hospital

Indianapolis, IN

Larry Widman

University of Oklahoma Health Sciences

Center

1 Goals

The goal of this project is to create universal identifiers (names and codes) to be used in the context of existing ASTM E1238, HL7, and CEN TC251 observation report messages employed in the various subdomains of healthcare informatics such as Clinical Laboratory Information Management Systems and Computer-Based Patient Record Systems.[6]^,7 Specifically, we want to create identifiers that can be used as the coded value of the "Observation Identifier" field (# 3) of the OBX segment of an ORU HL7 (HL7 Vs 2.2[8] or ASTM 1238-94[9]) message, or in a similar context in future versions of these HL7/ASTM standards. The LOINC codes will be identified in HL7 as code system "LN". The ultimate goal is that these "universal" identifiers, when used in the context of the messaging standards, will allow the exchange of clinical laboratory data between heterogeneous computing environments.

To facilitate this process, each identifier is to have a fully specified name that is created in a standard way so that users can create long names for their tests that can be linked to the universal test identifier using semi-automated methods. We have either begun, or plan, to link other code systems for tests observations such as the IUPAC/IFCC^2, ASTM E1238-94, SNOMED[10], and Euclides[11] codes to the LOINC codes. You will see a field in the LOINC database labeled for each of these extended codes.

We decided to focus on creating names for results of reportable tests (observations or measurements) rather than requestable batteries as our first effort, because the issues involved in naming results of tests are less complex than those involved in naming the batteries. Furthermore, defining the individual results is a prerequisite for defining the batteries that contain these individual tests. In addition, we can begin the process of transferring (and pooling) results once we have created unique identifiers for results. The names and identifiers of orderable batteries can be dealt with later.

Our goal is to create a "universal" master file of elected "test" names that will cover most of the entries in master files of operational laboratory systems, so that the terms in these operational master files could be mapped directly into universal codes and names. The names we create correspond most closely to the "long test descriptions" seen in test master files. We want to create "fully specified" names. That is, if a person wanted to map her local test dictionary to the LOINC codes, all information needed to map a local test name to one of the fully specified names should be present in the LOINC name. This means that the names created will usually be longer than those used in lab reports today. The fully specified LOINC name is not meant to be used on clinical reports. It is assumed that shorter, more convenient abbreviated names and synonyms will be created and maintained by the local computer system.

We want to achieve a level of detail in the definition of a test that will map one-to-one to the separately reported observations on a clinical laboratory report. If a test has its own column on a clinical report, or has a reference range that is different from other tests, or has clinical significance distinct from other closely related tests, it will usually be assigned a separate name. We deliver these fully specified names, their codes, and their related names as a database in which each line corresponds to a unique type of test.

1.1 What is not part of the name

Certain parameters and descriptions pertaining to test performance are specifically excluded from the fully specified test name. These parameters will typically be reported in separate fields (attributes) of a test report message, not as part of the name. Attributes that we explicitly exclude from the fully specified name are:

$ the instrument used in testing

$ fine details about the sample or the site of collection such as "right antecubital fossa"

$ the priority of the testing

$ who verified the result

$ the size of the sample collected

$ the place of testing (e.g. home, bedside, clinical lab)

The name does include information that identifies the type of sample. However, the "sample" part of the name is not meant to carry all possible information about the sample, but only enough to indicate significant differences in the result and to reflect current usage in names of tests. For example, laboratories usually define urine sodium, sweat sodium, and serum sodium as different tests because each of these has a different normal range. But laboratories do not define different tests to distinguish the concentration of arterial serum sodium from venous serum sodium, though the lab may report that the sample was venous or arterial in another part of the report. We are guided by the pragmatics of conventional usage. If laboratories define separate tests for the same measurements done on different specimens (this usually implies a well defined normal range difference), we will define different "resultable" tests in our dictionary. If they do not, we will not.

The extent to which we include methods as part of the name is also guided by pragmatics. We distinguish tests by the method used to produce the results only if the method has a significant effect on the interpretation of the result. This is a complex subject and it is difficult to fully describe our rationale in this report. Where laboratories do not tend to include the method in the name -- e.g., most of chemistry -- we do not include the method in the name. Where they tend to--e.g. in immuno-chemistry--we do. For some tests, this can be justified by the standardization of methods to produce "equivalent" results, and sometimes by the many variables (method, reagent) that one could never hope to represent them all in a single name.

The College of American Pathologists produces statistical summaries of the results for measurements of standard samples broken down by laboratory and by instrument or procedure. (These are called CAP surveys.) We explored the feasibility of using this CAP survey data to decide empirically when test names should be distinguished by method. This was not feasible because many of the apparent differences in method obtained with the standard samples were artifacts of the sample matrix and did not apply to serum specimens, and because the variation among laboratories was often of the same magnitude as the variation among methods.

This does not mean that we underrate the importance of differences in method. The result message will still include information about the normal range for that particular test, the source laboratory, and (if the laboratory wishes) specific information about the method. However, this information is reported in separate fields in the message. It is not embedded in the names of the test.

1.2 Scope of this document

The current scope of the existing LOINC database project includes all observations reported by clinical laboratories, including the specialty areas: chemistry, including therapeutic drug monitoring and toxicology; hematology; serology; blood bank; microbiology; and cytology. Anatomic and surgical pathology and cytology are within our scope, but have not yet been covered. In addition, the scope includes those non-test measurements that are commonly required to interpret test results and are usually included as part of the report with the laboratory observations. Examples include:

! for cervical pap smears, the phase of menstrual cycle use of estrogens

! for arterial blood gases, inspired dioxygen

! for drug concentrations used in pharmacokinetics, the dose

! for a blood bank, the number of units dispensed

To each name, we have assigned a unique permanent code that we call the LOINC code. This is the code that systems should use to identify test results in electronic reports. The LOINC code has no intrinsic structure except that the last character in the code is a mod 10 check digit. All of the structure associated with a single LOINC entity is stored in its record in the LOINC database. The algorithm to caluclate this check digit is given in Appendix B.

2 Major "Parts" of a Test/Observation Name

The fully specified name of a test result or clinical observation has five or six main parts including: the name of the component or analyte measured (e.g. glucose, propranolol), the property observed (e.g. substance concentration, mass, volume), the timing of the measurement (e.g. is it over time or momentary), the type of sample (e.g. urine, serum), the scale of measurement (e.g., qualitative vs. quantitative), and where relevant, the method of the measurement (e.g., radioimmune assay, immune blot). These can be described formally with the following syntax.

The colon character, ":", is part of the name and is used to separate the main parts of the name.

The first part of the name can be further divided up into four subparts, separated by carats (^). The first subpart can contain up to three levels of increasing taxonomic specification, separated by dots (.). The hierarchical structure is outlined in Table 2, with references to the section numbers where each item is explained in detail.

We used Tietz⁴, Henry³, IUPAC², EUCLIDES¹⁰, diagnostic microbiology textbooks such as Mahon and Manuselis[12] the American Association of Blood Banking¹², and other sources as well as the expertise of the individuals or the committee to choose preferred names.

Examples of fully specified LOINC names:

SODIUM:SCNC:PT:SER:QN

SODIUM:SCNC:PT:UR:QN

SODIUM:SRAT:24H:UR:QN

CREATININE.RENAL CLEARANCE:VRAT:24H:UR:QN

GLUCOSE^2H POST 100 G GLUCOSE PO:MCNC:PT:PLAS:QN

GENTAMICIN^TROUGH:MCNC:PT:SER/PLAS:QN

CALCIUM.FREE:SCNC:PT:SER/PLAS:QN

PROTEIN.ALBUMIN:MCNC:PT:SNV:QN

Table 2: Hierarchical Structure of Fully Specified Analyte Names
Level 1	Level 2	Level 3	Subpart Name	Section
1			Analyte/component	2.2
	1.1		Name and modifier	2.2.1
		1.1.1	Analyte/component name	2.2.1.1
		1.1.2	Analyte/component subname	2.2.1.2
		1.1.3	Analyte/component sub-sub-name	2.2.1.3
	1.2		Information about the challenge (e.g., 1H post 100 gm PO challenge)	2.2.2
	1.3		Adjustments/corrections	2.2.3
	1.4		"Person" (patient, donor, blood product unit)	2.2.4
2			Kind of Property (mass concentration, mass)	2.3
3			Time Aspect (point or moment in time vs. time interval)	2.4
4			System/Sample type (urine, serum)	2.5
5			Type of Scale (qualitative, quantiative, semiquantitative)	2.6
6			Method Type	2.7

2.1 General naming conventions

2.1.1 Abbreviations in names of component/analyte

Except for enumerated exceptions (Table 3), abbreviations should not be used in the fully specified analyte name. We require the use of "total" not "tot," "Fraction" not "frac," "alpha" not "A-," "Beta not B-" (and so on for any Greek letter), oxygen, not O_2, and so on. The exceptions that we plan to abbreviate in the analyte part of the name are shown in Table 3.

Table 3: Allowable Abbreviations in Analyte Names
AB	antibody
AG	antigen
AGGL	agglutination
CFU	colony forming unit
DNA	deoxyribonucleic acid
HIV	human immunodeficiency virus
HLA	human histocompatibility complex derived antigens
HTLV-1	human t-cell lymphotropic virus-1
IGx	immunoglobulins (e.g., IGG for immune globulin G, IGM for immune globulin M)
RNA	ribonucleic acid
RRNA	ribosomal nucleic acid

2.1.2 General naming rules for the analyte part of the fully specified name

2.1.2.1 Place the identifier of the substance being measured first. This means "Hepatitis A antibodies (AB)" not "Antibodies, Hepatitis A."

2.1.2.2 Use the generic name of a drug, not the brand name, when referring to drug concentrations and minimum inhibitory concentrations (MICs), e.g., Propranolol, not Inderal. For concentrations of drugs and sensitivity to antibiotics, we will usually include the brand or trade names in the field "related name".

2.1.2.3 Use fully taxonomic name of an organism or virus name (not the disease) when describing a test that diagnoses that disease. Say "rickettsia rickettsii AB" not "Rocky mountain spotted fever AB". Say "herpes simplex virus AB" not "HSV AB." The disease name should be included as a synonym in the Related Term field.

2.1.2.4 Species and groups of species: SP identifies a single species whose identity is not known. SPP identifies the set of species beneath a genus. We have a third case, however. In some tests, antibodies apply to different strains of species. In rickettsial diseases, the antibodies are then against groups of species, e.g. the spotted fever group or the typhus group. The convention remains the same: we name the immuno-chemical (serologic) test by the organism, so it becomes Rickettsia SPP.Spotted fever group, or Rickettsia SPP.Typhus group.

When the test measures an antigen to a specific species of organism but cross-reactivity is such that other organisms are identified, the name should be the principal organism which is targeted by the test.

2.1.2.5 Avoid "direct" and "indirect" except as parts of synonym names. Avoid conjugated and unconjugated when a more precise term is available. For instance, use bilirubin glucuronide instead of bilirubin conjugated. Bilirubin conjugated becomes the synonym.

2.1.2.6 Use "platelets," not "thrombocytes."

2.1.2.7 Name vitamins by their chemical name. E.g., use thiamin not Vitamin B1, The name containing "Vitamin" will be included as a synonym. This is the only reasonable approach because all vitamins have a chemical name but not all vitamins have a "numbered" vitamin name.

2.1.2.8 Always specify whether serology tests measure the antigen or antibody, using the abbreviation "AB" for antibody and "AG" for antigen. Remove the "anti" from "ANTI X AB." It is redundant and obscures the most significant word in the name. Thus, "anti-smooth muscle AB" becomes "Smooth muscle AB."

2.1.2.9 VDRL will be named Reagin AB because that is what it is. We will have to depend upon synonyms and aliases to equate our "standardized" names with the old names.

2.1.2.10 Use the noun form of the target of the antibody, e.g., Myocardium AB, not Myocardial AB.

2.1.2.11 Anion vs acid: Always use the anionic name for chemicals, not the acid name, e.g., lactate, citrate, and urate, not lactic acid, citric acid, and uric acid. The acid form of the name will be included in the synonym field of the database.

2.1.2.12 Alcohols: Always use the single-word names for alcohols: methanol, not methyl alcohol; ethanol, not ethyl alcohol, and so on.

2.1.2.13 Always spell out OH as Hydroxy, or as - ol, with no space or hyphen between Hydroxy and the next word.

2.1.2.14 Greek letters, alpha, beta, gamma, etc., are always spelled out (e.g., alpha tocopherol, not A-tocopherol), with a space between the spelled out Greek letter and the rest of the chemical name.

2.1.2.15 Use pH, not log(H+).

2.1.3 Punctuation in analyte names

A number of analyte names include punctuation characters such as commas, for example, to identify the position of multiple alkyl groups in a carbon chain. We will avoid special characters, e.g., commas, dashes, and parentheses, except where they are included in the name specified by IUPAC, the Chemical Abstract Service (CAS) convention, or another international convention. So commas will appear in multiple substitutions of alkyl chains per the CAS standard, dashes will appear in HLA antigen names, and parentheses (i.e. round brackets) will appear in the names of red blood cell antigens.

2.1.4 Case insensitivity

All names are case insensitive. We use upper case in our example, but senders and receivers could use upper, lower or mixed case. However, the meanings should not be sensitive to case conversions to avoid any possibility of confusion when the information is sent over networks that may apply case conversion. To identify parts of the few names that by international convention are case sensitive, such as red blood cell antigens, we use the word 'LITTLE' in front of the letter that is lower case. See examples in Table 4.

Table 4: Case Specifying Conventions
Our conventions	Standard mixed case
A LITTLE U (LITTLE A) AB	A u(a) AB
D LITTLE I (LITTLE A) AB	D i(a) AB
LITTLE I -1 AB	i-1 AB

2.1.5 Roman numerals vs. arabic numerals

Whenever possible, numerals shall be represented in their arabic form. However, when the conventional name uses Roman numerals as is the case for clotting factors such as factor VIII, the LOINC primary name will use Roman numerals and we define a synonym containing Arabic numerals.

2.2 Analyte/component (1st part)

The first main part consists of four subparts: (1) the principal name (e.g. the name of the analyte or the measurement); (2) the challenge or provocation, if relevant, including the time delay, substance of challenge, amount administered, and route of administration; (3) any standardization or adjustment; and (4) if the test relates to someone other than the patient, the relationship of the patient to that person (e.g., patient versus blood donor).

The four subparts of the first part follow this syntax:

<[analyte].[subclass].[sub-subclass]> ^

<[time delay] post [amount] [substance] [route])> ^

<adjustment> ^

<person>

In the above syntax, the carat (^) is a required delimiter and the "dot" (.) separates the analyte name from its subspecies.

This convention also implies that dots (.) and carats (^) cannot be a formal part of any of the words that are connected by these delimiters.

These subparts are described in greater detail below, Sections 2.2.1 through 2.2.4.

2.2.1 Analyte Name (1st subpart)

The first subpart names the analyte, including any relevant sub-classifications, separated from the main analyte name by dots.

2.2.1.1 Class/Subclass/Sub-subclass

The principal name (the first subpart) can be divided further by subclass (e.g. calcium (II) is one component, calcium.ionized is another test that measures a subclass of calcium.) Subclasses are separated by dots. Bound and free components, ionized and unionized components, and antibody subtypes are all subclasses. When the measurement includes all the subelements of the subclass, use the word "total," e.g., "Thyroxin.total".

If the antibody is from a particular subclass of antibodies specify the subclass (IGM, IGG, IGA, or IGD) e.g., Hepatitis A AB.IGG, Hepatitis A AB.IGM

If more than one species is included in the measurement, all are listed in the subclass, e.g. "Hepatitis A AB.IGM+IGG" with a plus sign (+) to separate the subspecies. There should be no spaces between the plus sign and the words it connects.

2.2.2 Challenge test (2nd subpart)

The second subpart contains information necessary to interpret "challenge" (or loading or tolerance) tests. Variables that report the result of a measurement taken a certain amount of time post challenge (e.g. glucose after an oral glucose tolerance test) must be distinguished according to the challenge and the time post challenge.

Thus, the second subpart has a substructure that identifies the time interval or time difference and the challenge, using the following syntax, where the word "post" (or base line) is required.

<time delay> "post" <challenge>

where the challenge can be further characterized as

<amount given> <substance/treatment given> <route given>

The time difference follows the syntax: n<S|M|H|D|W> where n is a number (possibly a decimal); S denotes seconds; M denotes minutes; H denotes hours; D denotes days; and W denotes weeks. The time delay can be preceded by a 'greater than' (>) sign, e.g. >4H.

Table 5 lists some possible values for time difference, but any time specification that follows the above syntax would be legal.

2.2.2.1 Reporting the baseline measure as part of a challenge test

We define one baseline term for different challenge batteries when the challenge is given by the same dose and route. So we define one baseline test for the 100 gm oral glucose tolerance test regardless of the number of separate measurements defined in the battery. For example, the baseline serum glucose for 100g oral glucose by mouth would be:

GLUCOSE^BS 100 G GLUCOSE PO

A laboratory could use this same test identifier to identify the baseline result of a 2 h glucose tolerance and a 3 h glucose tolerance, for example.

We would define different baseline measurements for challenges with different substances. The baseline serum glucose before a challenge with 50 U insulin challenge would be defined as a different test from the baseline glucose for an oral glucose tolerance test. These different baseline tests are defined to accommodate laboratories that conventionally do the same. However, a baseline glucose for any challenge is not affected by the challenge and could in principle be reported as a glucose without specifying the relation to a coming challenge.

We denote the route of the challenge by HL7 Version 2.2 "abbreviations for medication routes" (Table 6). An oral route of administration would be denoted by "PO," an intravenous route by "IV."

Examples

GLUCOSE^BS 100 G GLUCOSE PO:MCNC:PT:SER:QN

GLUCOSE^30M POST 100 GM GLUCOSE PO:MCNC:PT:SER:QN

GLUCOSE^2H POST 100 GM GLUCOSE PO:MCNC:PT:UR:QN

GENTAMICIN^TROUGH:MCNC:PT:SER:QN

For drug peak (obtained at a time presumed to reflect the highest concentration) and trough (obtained at a time presumed to reflect the lowest concentration) measures the nature of the substance loaded is the same as the analyte name, and need not be included.

Table 5: Time Delay Post Challenge
BS Baseline (time just before the challenge) PEAK The time post drug dose at which the highest drug level is reached (differs by drug) TROUGH The time post drug dose at which the lowest drug level is reached (varies with drug) RANDOM Time from the challenge, or dose not specified. (random)
n minutes/hours/days/weeks/months/etc. after challenge begun:
1M 1 minute post challenge 2M 2 minutes post challenge 3M 3 minutes post challenge 4M 4 minutes post challenge 5M 5 minutes post challenge 6M 6 minutes post challenge 7M 7 minutes post challenge 8M 8 minutes post challenge 9M 9 minutes post challenge 10M 10 minutes post challenge 15M 15 minutes post challenge 20M 20 minutes post challenge 25M 25 minutes post challenge 20M 30 minutes post challenge 1H 1 hour post challenge 2H 2 hours post challenge 2.5H 2 1/2 hours post challenge 3H 3 hours post challenge 4H 4 hours post challenge 5H 5 hours post challenge	6H 6 hours post challenge 7H 7 hours post challenge 8H 8 hours post challenge 8H SHIFT 8 hours alligned on nursing shifts 12H 12 hours post challenge 24H 24 hours post challenge 2D 2 days 3D 3 days 4D 4 days 5D 5 days 6D 6 days 7D 7 days 1W 1 week 10D 10 days 2W 2 weeks 3W 3 weeks 4W 4 weeks 1MO 1 month (30 days) post challenge 2MO 2 months (60 days) post challenge 3MO 3 months (90 days) post challenge

Table 6: Route Abbreviations for Challenge Part
AP B DT EP ET GTT GU IMR IA IB IC ICV ID IH IHA IM IN IO IP IS IT IU IV MTH	Apply Externally Buccal Dental Epidural Endotrachial Tube Gastronomy Tube GU Irrigant Immerse (Soak) Body Part Intra-arterial Intrabursal Intracardiac Intracervical (uterus) Intradermal Inhalation Intrahepatic Artery Intramuscular Intranasal Intraocular Intraperitoneal Intrasynovial Intrathecal Intrauterine Intravenous Mouth/Throat	MM NS NG NP NT OP OT OTH PF PO PR RM SD SC SL TP TRA TD TL UR VG VM WND	Mucous Membrane Nasal Nasogastric Nasal Prongs Nasotrachial Tube Ophthalmic Otic Other/Miscellaneous Perfusion Oral Rectal Rebreather Mask Soaked Dressing Subcutaneous Sublingual Topical Tracheostomy Transdermal Translingual Urethral Vaginal Ventimask Wound

2.2.2.2 Physiologic challenges

Some challenges are defined in terms of a physiologic stress, not a dose of a chemical substance. The LOINC names currently cover calorie fasts (no calorie intake), exercise, and fluid restrictions. These challenges are denoted by codes given in Table 7.

In the case of such challenges, the syntax also includes the duration of the challenge.

E.g., <duration> POST <duration><physiologic challenge>

E.g., CHOLESTEROL^POST 12H CFST

Table 7: Nature of Challenge
CFST	Calorie fast. No caloric intake (food) for the period specified in the time part of the term, e.g., 1 POST 12H CFST
EXCZ	Exercise undertaken as challenge (can be quantified)
FFST	Fluid "fast." No fluid intake for the period specified

The naming structure is an exact analogous structure to that of chemical challenges. A test for cholesterol after 12 hours of an energy fast would be represented as:

GLUCOSE^BS POST 12H CFST:MCNC:PT:SER:QN

In all physiologic challenges (fasting, fluid deprivation), the duration of the physiologic challenge must be stated.

A test for osmolality after fluid restriction would be

OSMOLALITY^POST 12H FFST:OSMOL:PT:UR:QN

A test for triglyceride after an 18 h for energy fast would be:

TRIGLYCERIDES.TOTAL^POST 12H CFST:MCNC:PT:SER:QN

Two durations can appear in one specification, e.g.:

CORTISOL^1.5H POST 0.05-0.15 U INSULIN/KG IV POST 12H CFST:MCNC:PT:SER:QN

Our rules for naming challenge tests work well only when there is a single intervention followed by a test for one or more components over time. Complex challenge tests involving more than one intervention or complicated sampling techniques need a unique name, but the name may not be a complete description of all of the test parameters.

2.2.2.3 Reporting characteristics of challenge as separate observations

Because we cannot anticipate every type of challenge and route of administration, and because some challenge tests have no usual dose, some challenge tests will not contain a dose. Challenge observations that do not include a specific dose in the name have the word "DOSE" where a numeric dose would otherwise appear. The general form is:

<analyte>^<time> post dose <route>

Examples:

GLUCOSE^1H POST DOSE PO:MCNC:PT:SER:QN

The actual dose might then be sent as a comment or as a separate "test" that carries the dose as its value. To accommodate laboratories that wish to transmit the relevant challenge dose as a separate observation, we also define separate test names (and codes) for reporting such doses. This dose could then be sent by the reporting service as a separate result in a separate OBX segment.

The name of the observation that identifies the value of the dose would have the form:

<drug or challenge substance>: <time> post dose <challenge substance>

Examples:

GLUCOSE^PO:MASS:PT:DOSE:QN

GENTAMICIN^IV:MASS:PT:DOSE:QN

Thus we distinguish a drug concentration from the drug dose by means of the data elements sample (4th part) of the test name (see Section 2.5). You can find the observations that carry the dose of drugs or challenges grouped in the class DRUG within the LOINC database. This approach has the advantages of parsimony and practicality. It also provides an observation ID for the piece of information that must be transmitted along with the request for the observation.

Another example would be:

OXYGEN:PRES:PT:BLDA:QN

OXYGEN INHALED:VRAT:PT:IHG:QN (liters/minute or milliliters/second)

OXYGEN INHALED MECHANISM:TYPE:PT:DOSE:QL (to report kind of delivery mechanism, e.g., nasal cannula)

An analogous approach is used for reporting many kinds of associated variables when the variables are not conventionally embedded in the name, in part because there are too many levels of the variables and it is not feasible.

2.2.3 Adjustments/corrections (3rd subpart)

The third subpart of the data element contains calculations that adjust or correct some measured value. We use this subpart to distinguish corrected or adjusted values from the uncorrected measurement, e.g., corrected cell counts from the raw cell counts. Since these attributes are unique to each measurement, they will be short phrases of text rather than a controlled vocabulary to define the content of the third subpart. However when defined, such a test will have a unique LOINC code and the meaning will be fixed by the text in the third part.

Examples:

CALCIUM.FREE^^PH ADJUSTED TO 7.4:SCNC:PT:SER/PLAS:QN

CREATININE.RENAL CLEARANCE^^NORMALIZED TO 1.72 BODY SURFACE AREA:VRAT:24H:UR:QN

LEUKOCYTES^^CORRECTED FOR NUCLEATED ERYTHROCYTES:NCNC:PT: BLD:QN

Note that the actual pH of the sample would be sent as a separate OBX segment in the test result message analogous to the approach described in Section 2.2.2.1.

We have not yet defined any observation codes that use this subpart. So you will not see any examples of this in the current (July 1995) LOINC database.

2.2.4 Person (4th subpart)

The fourth subpart of the analyte (component) distinguishes observations on the patient (or samples taken from the patient) from observations on non-patient materials that relate to the patient, e.g. a pack or unit of a blood product. This subpart can take on the values in Table 8:

Table 8: Relationship Modifier
CONTROL	Control
PATIENT	Patient
DONOR	Donor
BPU	Blood Product Unit (Pack)
FETUS	Fetus

Prothrombin time and blood bank observations provide examples of the fourth subpart. For prothrombin time, separate results are conventionally reported for the patient and the control. Use of PATIENT and CONTROL provides a method for distinguishing these two observations, e.g.:

PROTHROMBIN TIME^^^PATIENT:TIME:PT:BLD:QN

PROTHROMBIN TIME^^^CONTROL:TIME:PT:BLD:QN

Blood banks often report red blood cell antigens for the patient and for each blood product pack assigned to that patient. So we have:

RHESUS NOS AG^^^PATIENT:ACNC:PT:SER:SQ:AGGL

RHESUS NOS AG^^^BPU:ACNC:PT:SER:SQ:AGGL

2.3 Kind of Property (also called kind of quantity) (2nd part)

The second part of the fully specified name distinguishes between different kinds of quantities relating to the same substance: the mass versus the concentration of sodium in a urine sample, a molar concentration versus a mass concentration, or the absolute eosinophil count versus the percent of the total white count that are eosinophils. The type of property (kind of quantity) is an IUPAC concept described in the Silver Book.⁶ We include most of the relevant IUPAC types of property in Table 9.

Analytes reported with masses (mgs, gms, etc.) in the numerator of the units of measure are associated with one of the properties that begin with the word mass, e.g., mass content, mass concentration, etc. Analytes reported as moles or millequivalents in the numerator of units of measure are associated with properties that begin with the word substance, e.g., substance amount, substance concentration. Counts are associated with properties that begin with "number," e.g., a white blood cell count reported as number of WBCs divided by volume of blood, would have a property of Number Concentration. Measures of enzymatic activity are all associated with properties beginning with "catalytic."

Each of these four major property categories has five deriatives: content, concentration, concentration ratio, fraction, and rate. Measures of an amount (of mass, substance amount, catalytic activity, or number) divided by volume are concentrations. Mass concentration is mass divided by volume as in g/ml or g/dl. Measures of the total amount measured per sample are reported as contents (mass fraction, substance content, etc.). "Mass fraction" is used when X grams of component are found in Y grams of a sample. Typically mass fraction would have units of g/g = 1 = kg/kg. Morphology as a property indicates a pattern of distribution of a component or observation.

A mass ratio is the ratio of the mass of two chemical components in a sample. If the ratio refers to components in a single phase, the ratio of the mass concentrations is also a mass ratio because the denominators cancel out. So, a mass of serum creatinine to mass of serum urea nitrogen would be a mass ratio. Amount substituted would give a different ratio: SRTO.

IUPAC describes an entitic quantity. This refers to division by number of entities (e.g. cells, receptors, molecules).

Use "PRID" (presence or identity) as the type of property field when a specimen is sent for culture, and the result can be the presence of any organism (especially as an initial result) and later the organism is identified. The same rule applies to toxicology screens or other observations that report the identity of one or more classes of entities as the result. For example:

MICROORGANISM IDENTIFIED:PRID:PT:ISLT:QL:BACTERIAL SUBTYPING

MICROORGANISM IDENTIFIED:PRID:PT:ISLT:QL:VIRAL SUBTYPING

All clearances have the property of volume rate, but "Clearance" will be included in analyte name to clarify meaning:

SODIUM RENAL CLEARANCE:VRAT:24H:UR:QN

CREATININE RENAL CLEARANCE:VRAT:12H:UR:QN

Table 9: Kind of Property
Enzymatic Activity		Other Properties
CACT	*Catalytic Activity	ABS	Absorbance
CCNC	*Catalytic Concentration	ACT	*Activity
CCRTO	Catalytic Concentration Ratio	APER	Appearance
CCNT	*Catalytic Content	ARB	*Arbitrary
CFR	*Catalytic Fraction	AREA	Area
CRAT	*Catalytic Rate	ASPECT	Aspect
CRTO	Catalytic Ratio	CLAS	Class
Entitic		CNST	*Constant
ENT	*Entitic	COEF	*Coefficient
ENTSUB	*Entitic Substance of Amount	COLOR	Color
ENTCAT	*Entitic Catalytic Activity	CONS	*Consistency
ENTNUM	*Entitic Number	DEN	Density
ENTVOL	*Entitic Volume	DEV	Device
Mass		DIFF	*Difference
MASS	Mass	ELAS	Elasticity
MCNC	*Mass Concentration	ELPOT	Electrical Potential (Voltage)
MCRTO	Mass Concentration Ratio	ELRAT	Electrical Current (Amperage)
MCNT	Mass Content	ELRES	Electrical Resistance
MFR	*Mass Fraction	ENRG	Energy
MINC	*Mass Increment	EQL	*Equilibrium
MRAT	Mass Rate	FORCE	Mechanical force
MRTO	Mass Ratio	FREQ	Frequency
Counts		IMP	Impression/ interpretation of study
NUM	*Number	KINV	*Kinematic Viscosity
NCNC	*Number Concentration	LEN	Length
NCNT	Number Content	LINC	*Length Increment
NFR	*Number Fraction	LIQ	*Liquifaction
NRTO	Number Ratio	MGFLUX	Magnetic flux
Substance Amount (Moles/Millequivalents)		MORPH	Morphology
SUB	*Substance Amount	MOTIL	Motility
SCNC	*Substance Concentration	OD	Optical density
SCRTO	*Substance Concentration Ratio	OSMOL	*Osmolality
SCNT	*Substance Content	PRID	Presence/Identity
SCNTR	*Substance Content Rate	PRES	*Pressure (Partial)
SFR	*Substance Fraction	PWR	Power (wattage)
SCNCIN	*Substance Concentration Increment	RANGE	Ranges
SRAT	*Substance Rate	RATIO	Ratios
SRTO	*Substance Ratio	RDEN	Relative Density
Volumes		REL	*Relative
VOL	*Volume	SATFR	*Saturation Fraction
VCNT	*Volume Content	SHAPE	Shape
VFR	*Volume Fraction	SMELL	Smell
VRAT	*Volume Rate	SUSC	Susceptibility
VRTO	*Volume Ratio	TASTE	Taste
Miscellaneous Unit Measures		TEMP	*Temperature
ACNC	Concentration, Arbitrary Substance	TEMPDF	*Temperature Difference
RLMCNC	*Relative Mass Concentration	TEMPIN	*Temperature Increment
RLSCNC	*Relative Substance Concentration	TITR	Dilution Factor (Titer)
THRACNC	Threshold Arbitrary Concentration	TYPE	Type
THRMCNC	*Threshold Mass Concentration	VEL	*Velocity
THRSCNC	*Threshold Substance Concentration	VELRT	*Velocity Ratio
	Time	VISC	Viscosity
TIME	Time (e.g. seconds)
TMDF	*Time Difference
TMSTP	Time Stamp -- Date and Time
TRTO	Time Ratio
RCRLTM	*Reciprocal Relative Time
RLTM	*Relative Time
*Starred items are adopted from the IUPAC Silver Book,2 non-starred items are extensions.

2.4 Time Aspect (Point or moment in time vs. time interval) (3rd part)

One can measure a property at a moment (point) in time or over a time interval and integrate, in the mathematical sense, over time. In the latter case, we aggregate a "series" of physiologic states into a single scalar value that reflects some "average" property measured over the specified time interval. Intervals also have relevance for rate measurements such as excretion (substance rate or mass rate) or clearances (volume rates). The amount over an interval is often expressed as a mass rate (MRAT) or a substance rate (SRAT, e.g., mol/d). Interval measurements often apply to urine and stool (e.g., collection over 24 h and calculation of a concentration, total amount, or clearance). They also apply to clinical measurements such as urine outputs where we have shift totals and 24 h totals, and event counts on physiologic monitors such as the number of premature ventricular contractions (PVCs) over 24 h on a Holter monitor.

The allowed values are defined as a syntax exactly like the syntax for the times in challenge tests, e.g., <numeric value><S|M|H|W> The most common one is 24H. Table 10 gives some other examples.

For urine 24 h collection is the "standard" integrated measure and these are almost always reported as mass (MRAT), amount of substance (SRAT), or catalytic (CRAT) rates. These would contrast with spot or random urines which are represented as point (PT) measures in our nomenclature and usually reported as concentrations -- MCNC, CCNC, or SCNC for mass, catalytic, and substance concentrations respectively.

The designation of 24 h collection is maintained for tests that traditionally have reference ranges based on amount of substance of a component cleared or excreted in 24 h. However, a given specimen could have a 23 h collection time and would still be called as a 24 h study. Depending upon the policies and procedures of the lab, they might extrapolate the reported value to what it would have been if the collection was the full 24 hours and report it as moles per day.

Table 10: Duration Categories
PT	To identify measures at a point in time. This is a synonym for "spot" or "random" as applied to urine measurements.
* (star)	Life of the "unit." Used for blood products.
30M	30 minutes	7H	7 hours	6D	6 days
1H	1 hour	8H	8 hours	1W	1 week
2H	2 hours	12H	12 hours	2W	2 weeks
2.5H	21/2 hours	24H	24 hours	3W	3 weeks
3H	3 hours	2D	2 days	4W	4 weeks
4H	4 hours	3D	3 days	1MO	1 months (30 days)
5H	5 hours	4D	4 days	2MO	2 months
6H	6 hours	5D	5 days	3MO	3 months

Drug doses (as required to report the mass or amount of substance of a drug given) would be identified by recording "DOSE" as the system (sample) and "MASS" as the kind of quantity. A point dose would be the dose given at a single point in time (e.g., 250 mg of ampicillin). To represent the total amount of a drug given in 24 h, one would record "24H" in the third subfield.

Example:

GENTAMICIN:MASS:PT:DOSE:QN

GENTAMICIN:MASS:24H:DOSE:QN

The instrument rate of dosing (mgs/hr) as could be measured from any drug-infusion pump at a moment in time would be:

GENTAMICIN:MRAT:PT:DOSE:QN

The average rate of dosing over a period of time would be:

GENTAMICIN:MRAT:24H:DOSE:QN

Although we describe a number of ways to use these naming rules, we have not yet implemented all of them in the July 1995 LOINC database.

Sample volumes reported for timed measurements are carried in other fields or as separate "test" results in other OBX segments.

2.5 System/Sample Type (4th part)

System/sample type is the fourth part of the fully specified test name. Sample type should be represented with the abbreviations in Table 11 (which include most of the sample types defined in ASTM E1238-94, and HL7 version 2.2). These do not include every conceivable variant, just the major types.

The system/specimen type part of the name is required. We have not defined different tests for every combination of component (analyte) and type of system/sample , just those that are commonly reported as such. In practice, laboratories include a relatively small range of body materials in the their test names. Chemical tests commonly distinguish between serum, urine, blood, and cerebrospinal fluid. Microbiology cultures tend to distinguish between a greater number of sources. The list in Table 11 was defined for reporting sample type in a field of the HL7/ASTM message that is quite independent of the name, and we do not imply that all such types will find their way into distinct LOINC names. However, when a distinction by type of system is required in the name, it should be represented by one of the codes given in Table 11.

Immunochemical tests have been standardized for very few types of body material: serum, CSF, and not much else. When should we lump a variety of specimen types under the unspecific code FLU and when we should give a body material its own unique name for a given component? The decision depends upon the degree to which laboratories have reported the system-component pair as a separate "result" and the degree to which the normal ranges for a given component-system have been standardized. By this rule, we will always define different tests for serum and for urine, when a component can be measured in both. We define the pair SODIUM/SWT (sweat) because it is a standardized test used to diagnose cystic fibrosis. We will not define the pair SODIUM/DUFL (duodenal fluid) because such measures have not been standardized. This does not mean that the specifics about the system would be ignored. It just means that this information would be recorded in another field of the message (the specimen field of the HL7 OBR segment), not in the name.

For many chemistry tests we have included in the LOINC database a test name for identifying miscellaneous types of body material (fluid other), to provide a way to distinguish tests that are performed on types that are not explicitly represented in the database. We use the code XXX to identify a material that is not specified , it could be solid or fluid, for example.

For many types of tests, the distinction between plasma and serum is irrelevant. When testing on serum or plasma is clinically equivalent, the system should be recorded as SER/PLAS. The same is true of serum and blood (SER/BLD), or even all three (SER/PLAS/BLD). Sometimes the test can only be run on plasma or on serum; the component will then be associated with either SER or PLAS but not both. If the test can be run on either but the results are different and standardized (a very rare circumstance), two separate tests will be defined in our file, one with a system PLAS and one with a system SER.

If the test is run on a combination of types of system (such as a ratio of substance found in CSF and plasma) the codes are joined with a "+" : CSF+PLAS, CSF+SER, etc.

Table 11: System/Sample Type Codes
ABS AMN ASP BPH BIFL BLDA BBL BLDC BLDCO BPU BLDV BON BRTH BRO BRN CALC CDM CNL CTP CSF CVM CVX COL CNJT CUR CYST DIAF DOSE DRN DUFL EAR EARW ELT ENDC ENDM EOS RBC EYE EXHLD FIB FLT FIST	Abcess Amniotic fluid Aspirate Basophils Bile fluid Blood arterial Blood bag Blood capillary Blood - cord Blood product unit Blood venous Bone Breath (use EXHLD) Bronchial Burn Calculus (=Stone) Cardiac muscle Cannula Catheter tip Cerebral spinal fluid Cervical mucus Cervix Colostrum Conjunctiva Curettage Cyst Dialysis fluid Dose med or substance Drain Duodenal fluid Ear Ear wax (cerumen) Electrode Endocardium Endometrium Eosinophils Erythrocytes Eye Exhaled gas (=breath) Fibroblasts Filter Fistula	FLU GAS GAST GEN GENC GENL GENV HAR IHG IT ISLT LAM WBC LN LNA LNV LIQ LYM MAC MAR MEC MBLD MLK MILK NAIL NOS ORH PAFL PAT PRT PLC PLAS PLB PLR PMN PPP PRP PUS SAL SEM SER	Body fluid, unsp Gas Gastric fluid/contents Genital Genital cervix Genital lochia Genital vaginal Hair Inhaled Gas Intubation tube Isolate Lamella Leukocytes Line Line arterial Line venous Liquid NOS Lymphocytes Macrophages Marrow (bone) Meconium Menstrual blood Milk Breast milk Nail Nose (nasal passage) Other Pancreatic fluid Patient Peritoneal fluid /ascites Placenta Plasma Plasma bag Pleural fluid (thoracentesis fld) Polymorphonuclear neutrophils Platelet poor plasma Platelet rich plasma Pus Saliva Seminal fluid Serum	SKN SKM SPRM SPT SPTC SPTT STON STL SWT SNV TEAR THRT THRB TISS TISG TLGI TLNG TISPL TSMI TISU TUB ULC UMB UMED URTH UR URC URT URNS USUB VOM BLD BDY WAT WICK WND WNDA WNDE WNDD XXX	Skin Skeletal muscle Spermatozoa Sputum Sputum - coughed Sputum - tracheal aspirate Stone (use CALC) Stool = Fecal Sweat Synovial fluid (Joint fluid) Tears Throat Thrombocyte (platelet) Tissue, unspecified Tissue gall bladder Tissue large intestine Tissue lung Tissue placenta Tissue small intestine Tissue ulcer Tube, unspecified Ulcer Umbilical blood Unknown medicine Urethra Urine Urine clean catch Urine catheter Urine sediment Unknown substance Vomitus Whole blood Whole body Water Wick Wound Wound abscess Wound exudate Wound drainage To be specified in another part of the message

We will be specific about the type of system to distinguish at least among blood, urine, cerebrospinal fluid, pleural fluid, synovial fluid, and peritoneal fluid.

Details about the exact source and collection method (e.g. blood drawn from the right arm and maintained on ice) are not a proper part of the test name and are reported in other parts of the message, e.g., OBX and OBR of the HL7 definition.

2.6 Type of Scale (5th part)

The fifth data part of the test name specifies the manner of testing, and is a required part. The abbreviation of the type of scale (previously called precision), given in Table 12, should be used in the fully specified name.

Table 12: Type of Scale
Type of Scale	Abbr.	Description
Quantitative	QN	The result of the test is a numeric value that relates to a continuous numeric scale. Reported either as an integer, a ratio, a real number, or a range. The test result value may optionally contain a relational operator from the set {<=, <, >, >=}. Valid values for a quantitative test are of the form "7", "-7", "7.4", "-7.4", "7.8912", "0.125", "<10", "<10.15", ">12000", 1-10 etc.
SemiQuant	SQ	Ordered categorical responses , e.g. 1+, 2+, 3+ ; positive, negative; reactive, indeterminant, nonreactive.
Qualitative (Nominal)	QL	Nominal or categorical responses that do not have a natural ordering. e.g. names of bacteria (reported as answers); categories of appearance, e.g., yellow, clear, bloody.

2.7 Type of Method (6th part)

The method by which the test was performed is the sixth part of the test name. Methods need only be expressed as part of the name when they provide a distinction between tests that measure the same component (analyte) but which have different clinical significance or have a different clinical reference ranges. For instance, whole blood glucose tested with a chemstrip might be distinguished in the method field.

Laboratories do not include the method as part of the name for most common chemical and hematological tests. They often need the freedom to choose the instrument according to time of day, urgency of the request for service, availability of the instruments and so on, even though the instruments may employ different methods. The laboratories then adjust each of the "interchangeable" instruments to produce equivalent results even though the instruments may use

Table 13: Methods
Method	Abbr	Explanation	Method	Abbr	Explanation
ACID-FAST STAIN.KINYOUN			MACCHIAVELLO STAIN
ACID-FAST STAIN.KINYOUN MODIFIED			MALARIA THICK SMEAR
ACID-FAST STAIN. ZIEHL-NEELSEN			MANUAL COUNT
	ACIF		MINIMUM BACTERICIDAL CONCENTRATION	MBC
ACRIDINE ORANGE STAIN			MEASURED
AEROBIC CULTURE	AC		METHAMINE SILVER NITRATE STAIN
ACID-FAST BACILLI CULTURE	AFB		METHYLENE BLUE STAIN.LOEFFLER
AGAR DIFFUSION	BS	Bacterial sensitivity (Kirby-Bauer)	MINIMUM INHIBITORY CONCENTRATION	MIC
AGGLUTINATION	AGGL		MICROSCOPIC COUNT	MC
AGGLUTINATION -- LATEX	LA		MICROSCOPY.LIGHT
AGGLUTINATION -- RED BLOOD CELL	AGGL RBC	Blood bank typing	MYCOBACTERIAL SUBTYPING
ALKALI DENATURATION	AC		NEISSER STAIN
ANAEROBIC CULTURE	ANC		NEUTRALIZATION	NEUT
AUTOMATED			ORGANISM-SPECIFIC CULTURE	OSC
BACTERIAL SUBTYPING			OVA AND PARASITE PREPARATION
BLOOD CULTURE			OXIMETRY
CALCOFLUOR WHITE PREPARATION			PCR/PROBE
CARBOL-FUCHSIN STAIN			PERIODIC ACID-SCHIFF STAIN
COMPLEMENT FIXATION	CF		PINWORM EXAMINATION
CHEMICAL SEPARATION		As distinguished from electrophoresis	PLATELET AGGREGATION
CHROMATOGRAPHY.COLUMN			PRICE-JONES
COUNTER-IMMUNOELECTROPHORESIS	CIE		QUICK METHOD
COAGULATION ASSAY	COAG	To distinguish coagulation tests based on activity	REES-ECKER
CYSTIC FIBROSIS RESPIRATORY CULTURE			REFRACTOMETER
DARK FIELD EXAMINATION			REINSCH
DIRECT BURN CULTURE			RESPIRATORY CULTURE
DNA PROBE			RHODAMINE-AURAMINE FLUOROCHROM
DRY MOUNT		Of slides, as distinguished from wet mount.	RADIOIMMUNOASSAY	RIA
DUKE			ROUTINE FUNGAL CULTURE
ELECTROPHORESIS			SERUM BACTERICIDAL TITER	SBT
ELECTROPHORESIS PH 6.3			SHEEP CELL AGGLUTINATION
ELECTROPHORESIS PH 8.9			SPUN
ENZYMATIC ASSAY	ENZY	To distinguish coagulation assays based on enzymatic activity	STATED
FLOCCULATION ASSAY	FLOC		STERILE BODY FLUID CULTURE
FLOW CYTOMETER			STOOL CULTURE
FUNGAL BLOOD CULTURE			TEST STRIP AUTO
FUNGAL SUBTYPING			TEST STRIP MANUAL
GIEMSA STAIN			THROAT CULTURE
GIMENEZ STAIN			TOLUIDINE BLUE O STAIN
GRAM STAIN			TRICHROME STAIN
HEMAGGLUTINATION INHIBITION	HAI		TURBIDIMETRY
HEMATOXYLIN AND EOSIN STAIN			URINE CULTURE
IMMUNE BLOT	IB		VISUAL COUNT	VC
IMMUNE DIFFUSION	ID		VIRAL SUBTYPING
IMMUNE FLUORESCENCE	IF		VIRUS CULTURE
	IMM		W/O TITRATION
IMMUNE ELECTROPHORESIS	IMM ELECT		W/TITRATION
IMMUNE ASSAY	IMM-ASS		WARTHIN-STARRY STAIN
IMMOBILIZATION			WESTERGREN
INDIA INK PREPARATION			WET MOUNT		Of slides (contrast dry mount)
INTRAVASCULAR LINE CULTURE			WINTROBE
IVY			WITH P-5'-P
KLEIHAUER-BETKE			WITHOUT P-5'-P
KOH PREPARATION			WRIGHT STAIN
LEE WHITE			WRIGHT/GIEMSA STAIN
M'FADYEAN STAIN			ZETAFUGE

different methods. So, we do not want to distinguish too finely on the basis of methods. Though method is rarely significant for many chemical and hematological tests, it is more often important to immunochemical/serology testing, because the sensitivity and specificity of some tests varies greatly with the method. So you will see methods entered more commonly in immunochemical tests within the LOINC database.

This does not meant that information about the method is not relevant at all, but that it is often not a meaningful part of the test name. It is an essential element of the internal quality assurance of laboratories. Remember that both reference range and method can be sent in other fields of ASTM, HL7, and CEN TC251 result messages.

3 Special Cases

3.1 Findings viewed as variables or as values

For some complex tests there are two ways to organize the results into a report.

3.1.1 Binary scale panel approach

Assume a set "X" is made up of five "results" that can have a scale of (absent present) or (0 1). These results could be reported as:

Finding 1 = Present or as 1

Finding 2 = Absent 0

Finding 3 = Present 1

Finding 4 = Absent 0

Finding 5 = Absent 0

Each finding is then considered a binary variable. This is sometimes called a "panel" approach.

3.1.2 Multiple Choice/Multiple Answer Approach

The alternative would be to report this information as a single variable (or multiple-choice question) with many possible values:

Variable X - Finding 1, Finding 3

In this case the findings are the values of a variable called Variable X; only the positive findings are reported as values. Many laboratory tests, e.g., those that test for HLA antigens, red blood cell antigens, or screens for toxic substances, could in theory be presented either way. The microscopic part of the differential count and urinalysis could also be described either way. History and physical findings and (given a real stretch) even culture results could be structured in the panel or multiple choice/multiple answer format.

A single lab may report red blood cell antigens in either way, as a binary panel or a multiple-choice result, depending upon the purpose of the test. The routine cross and type are reported out in the multiple choice pattern format (only positives from a modest fixed set of tested antigens are reported). But if the tests are being used to prove fatherhood, the results are usually reported as a binary panel.

Blood cultures could in theory be regarded as panels:

Test Name Value

E.Coli absent

Staph aureus present

Diptheroids absent

Pneumococcal pneumonia absent

Pseudomonas present

although in practice such tests are almost always reported in the multiple choice/multiple answer format, as follows:

Test Name Values

Blood culture Pseudomonas, Staph aureus

We bring up these issues to explain why we use a somewhat different data format for some types of tests, and why we sometimes provide for both reporting methods (e.g., HLA blood cell antigen tests) in the LOINC database. When a binary scale is used, the kind of property will usually be arbitrary concentration (ACNC). When the multiple-choice multiple-answer approach is used, the scale will be nominal and the type of property will be presence or identification (PRID).

3.2 Blood bank

Red cell antigens will be named in accordance with the American Association of Blood Banking (A/AB/B) naming standards.[13] In addition to the antigen or antibody, a modifier would be included in the fourth subfield of the first field, to indicate whether testing was performed on the patient, donor, or blood pack. Unless explicitly stated, testing is assumed to have been on a material collected from a patient. Additional information about the person identified in the fourth subpart, such as the donor's name or relationship to patient, should be placed in other OBX segments, or comment segments of the message, and would not be part of the test name.

Examples of blood bank related names:

ANTIBODIES IDENTIFIED^^^PATIENT:PRID:PT:SER:SQ

B AB^^^DONOR:ACNC:PT:SER:QL:AGGL RBC

Each reportable antigen must have its own test, so that each element in a full set of binary tests could be reported as (negative positive) or (0 1).

The fully specified names of A, AB, and O blood types (as observations) would be as follows:

Measure of serum antibody against type A blood of donor:

A AB^^^DONOR:ACNC:PT:SER:QL:AGGL RBC

Presence of A antigen on donor's red blood cells:

A AG^^^DONOR:ACNC:PT:RBC:QL:AGGL RBC

Presence of A antigen on the blood cells in a pack of blood given to the patient:

A AG^^^BPU:ACNC:PT:RBC:QL:AGGL RBC

Blood bank reporting illustrates the need for a method of reporting by panel and by multiple-answer mechanism. The LOINC database provides observation names for both kinds of reporting.

B AG^^^BPU:ACNC:PT:RBC:SQ:AGGL RBC

ANTIGENS ABSENT^^^BPU:PRID:PT:BBL:SQ

The LOINC database provides other "observations" for reporting: the status of each blood pack (e.g. held, given, discarded), and for reporting that information when HIS and medical records systems want it; how much of each type of blood product was given at a moment in time; the type of each pack; any adverse reaction to that pack; and the pack number to accommodate laboratories that send this information as discrete observations.

BLOOD PRODUCT DISPOSITION:TYPE:PT:BPU:QL

BLOOD PRODUCT TYPE:TYPE:PT:BBL:QL

3.3 Immunocompetence studies

The T-cell markers in the LOINC database include all of the single markers and the most commonly reported combinations, e.g. "CD10+CD20+". These will probably be expanded in later editions of the LOINC database.

The database also includes fully specified names for all of the commonly reported HLA antigens. These are grouped in the class HLA. Experimental methods can define many subtypes of many antigens, so this list is not exhaustive, and is also likely to expand with time.

Example:

HLA-A1^^^PATIENT:ACNC:PT:BLD:SQ

3.4 Naming results of microbiological culture

The inherent complex structure of results of microbiological culture presents unique challenges for standard names.

Result Status (Preliminary, Final) will be indicated in the OBR segment of HL7⁷ segment with the Result Status field (OBR-25), not as part of the name.

Specimen Type (Serum, Blood, Urine, etc.) will be indicated in the HL7 OBR segment with the Specimen Source field (OBR-15), but may also be represented in the name.

Details of specimen collection will usually be noted as OBX segments or comment segments that accompany the culture result message. The observation identifier for the OBX segment will have the fully specified name of "Specimen Collection Description:NOS:QLS" and the Observation Sub-ID field will be used to order or group sets of observations. That is, if the material was collected by swabbing a wound of the right upper arm, multiple OBX segments would be created, each with the name "Specimen Collection Description:NOS:QLS," and the Observation Results fields of the OBX segments would contain respectively "Swab," "Right," "Arm," and "Wound." (The granularity of the actual terms used in the specimen description is at the discretion of the user. Thus, "Right Arm Wound" as the value of a single OBX segment could be used in place of the three codes described in the previous sentence.)

Descriptions of measurement and culture growth will be noted as separate OBX segments that accompany the culture result message. The name of the observation identifier will provide the context of the observation. For instance, the name for a quantitative test of bacteria in a specimen would be:

COLONY COUNT:NUM:PT:XXX:QN:VC

Descriptions of Gram stain findings will be noted as OBX segments that accompany the culture result message. The name of the observation identifier will be:

MICROSCOPIC OBSERVATION:PRID:PT:XXX:QL:GRAM STAIN

The result values that could be reported with this test (which is a multiple-choice, multiple answer type or observation) might include one or more of the following:

Epithelial cells

Gram positive cocci in chains

Many Gram negative diplococci

The organisms identified in a culture will be sent as result values in OBX segments. A separate table of allowable organism names will need to be identified. (Bergey's Manual of Determinative Bacteriology[14] or some other authoritative source may be used as the standard.) The names for the result identifiers will be created using the same strategy as for other identifiers but with particular emphasis on the method. While "Throat Culture" is the source of the culture inoculum, it is also a label that indicates what kind of media was inoculated and the other techniques used in the laboratory. So, it is a short hand for a kind of method and such will be recorded as the method part of the name. Thus, "Throat Culture," and "Blood Culture," and "Clostridium difficile Culture," all represent labels for how a culture was performed. Examples of names of culture results are:

MICROORGANISM IDENTIFIED:PRID:PT:BLD:QL:BLOOD CULTURE

MICROORGANISM IDENTIFIED:PRID:PT:BRN:QL:DIRECT BURN CULTURE

MICROORGANISM IDENTIFIED:PRID:PT:STL:QL:STOOL CULTURE

Names of methods of staining directly on a sample/material (where many descriptive observations are possible):

MICROSCOPIC OBSERVATION:PRID:PT:XXX:QL:GRAM STAIN

MICROSCOPIC OBSERVATION:PRID:PT:XXX:QL:ACID FAST STAIN.KINYOUN

MICROSCOPIC OBSERVATION:PRID:PT:XXX:QL:DRY MOUNT

MICROSCOPIC OBSERVATION:PRID:PT:XXX:QL:INDIA INK PREPARATION

MICROSCOPIC OBSERVATION:PRID:PT:XXX:QL:TRICHROME STAIN

MICROSCOPIC OBSERVATION:PRID:PT:XXX:QL:GIEMSA STAIN

Because of the alternative representation of microscopic observations (see discussion in 1.1 of LOINC and item 21) the following convention will be used for the alternate representation of microscopic examinations:

WBC CASTS:ACNC:PT:URNS:SQ:MICROSCOPY.LIGHT

RBC CASTS:ACNC:PT:URNS:SQ:MICROSCOPY.LIGHT

EPITHELIAL CELLS:ACNC:PT:URNS:SQ:MICROSCOPY.LIGHT

Names for results of staining procedures performed on organisms that are growing in culture will use Isolate (ISLT) as the system/sample type. For example:

MICROORGANISM IDENTIFIED:PRID:PT:ISLT:QL:FUNGAL SUBTYPING

Names for organism-specific cultures (OSC):

BRUCELLA SP:PRID:PT:BLD:QL:ORGANISM SPECIFIC CULTURE

BORDETELLA PERTUSSIS:ACNC:PT:THRT:SQ:ORGANISM SPECIFIC CULTURE

GROUP B STREPTOCOCCUS:PRID:PT:THRT:QL:ORGANISM SPECIFIC CULTURE

CHLAMYDIA SP:PRID:PT:GEN:QL:ORGANISM SPECIFIC CULTURE

LEGIONELLA SP:PRID:PT:SPT:QL:ORGANISM SPECIFIC CULTURE

Names for method for general class of organism:

FUNGUS IDENTIFIED:PRID:PT:WND:QL:ROUTINE FUNGAL CULTURE

MICROORGANISM IDENTIFIED:PRID:PT:CSF:QL:STERILE BODY FLUID CULTURE

Again, the Result Value of these tests would be either organism names or other statements of culture outcome. Table 14 contains valid values of the culture result OBX segment:

Table 14: Example Culture Results

No growth

Gram-positive cocci

Small Gram negative rod

Escherichia coli

Normal flora

Candida albicans

Drug-susceptibility tests will be named according to the generic name of the drug tested and the methodology used in testing, with the property SUSC, with values that are either QN or SQ. Thus, appropriate names would be:

AMPICILLIN:SUSC:PT:ISLT:QN:MIC

AMPICILLIN:SUSC:PT:ISLT:SQ:AGAR DIFFUSION

TICARCILLIN+CLAVULANATE:SUSC:PT:ISLT:QN:MBC

Table 15 lists methods in drug-susceptibility tests.

Table 15: Drug Susceptibility Methods
AGAR DIFFUSION	Bacterial sensitivity (Kirby-Bauer)
MIC	Minimum inhibitory concentration
MBC	Minimum bactericidal concentration
SBT	Serum bactericidal titre

The drug susceptibility tests are all grouped together in the LOINC database under the class ABXBACT.

3.5 Skin tests

These follow the pattern of a challenge test. For a TB skin test it would be:

TUBERCULOSIS REACTION WHEAL^3D POST 25 U TU ID:LEN:PT:SKN:QN

Where TU means tuberculin units, ID means intradermal, LEN indicates a measure of length (the diameter of the wheal) and so on.References

Appendix A -- LOINC Database Structure

# Field Name Type Width Description

1 LOINC_CODE Character 6

2 COMPONENT Character 150

3 PROPERTY Character 10

4 TIME_ASPCT Character 10

5 SYSTEM Character 20

6 SCALE_TYP Character 30

7 METHOD_TYP Character 30

8 RELAT_NMS Character 240

9 CLASS Character 8

10 SOURCE Character 8

11 EUCLIDE_CD Character 10

12 ASTM_CD Character 9

13 IUPAC_CD Character 8

14 DT_LAST_CH Date 8

15 CHNG_REAS Character 200

16 CHNG_TYPE Character 3

17 COMMENTS Character 254

18 ANSWERLIST Character 200

19 STATUS Character 3

20 MAP_TO Character 6 Maps old term to new

21 SCOPE Character 254

22 SNOMED_CD Character 10

23 VA_CD Character 8

24 METPATH_CODE Character 10

25 HCFA_CODE Character 12

26 CDC_CODE Character 6

27 NORM_RANGE Character 30 Sample normal ranges

28 UNITS Character 20 Example unit

29 OTHR_UNITS Character 20

30 GPI_CD Character 11

31 GPI_CD_TOTAL Character 254

32 REFERENCE Character 254

Field 1 contains the unique LOINC Code. This is a numeric code with a mod 10 check digit. (The algorithm for calculating a mod 10 check digit is given in Appendix A.)

Fields 2-7 contain the six parts of the name. The fully specified name for a given LOINC code would be constructed by printing out the contents of these fields (2-7), inserting a colon (:) between the contents of each of these fields. Note: in this version, we have changed the nomenclature for these fields, to better coordinate with IUPAC:

Old New

precision scale

timing time aspect

analyte component

specimen system

Field 8 - Related Terms, contains one or more synonyms. When the field contains many related terms, they are separated by semicolons (;). This field is intended to make it easier to find a given observation by providing other names by which the observation may be known. For a drug level, for example, we include the trade names of that drug under the related names. The related names apply principally to the first part of the fully specified name.

Field 9 - Class, is an arbitrary classification of the terms designed principally to parcel out work to committee members and to group related observations together. The current classifications are listed in Table 16. We present the database sorted by the class field. But users of the database should feel free to re-sort the database in any way they find useful, and/or to add their own classifying fields to the database. In this release, we have combined the previous classes BACT, PROBE, and VIRO, and the terms in the SERO class which described infectious agents, into a new class MICRO.

Table 16: Classes
ABXBACT	Antibiotic susceptibility
BC	Cell counts (blood, CSF, pleuretic fluid)
BLDBK	Blood bank
CHAL	Challenge tests
CHALSKIN	Skin challenge tests
CHEM	Chemistry
CLIN	Clinical terms for reporting patient clinical state
COAG	Coagulation study
DRUG	Drug levels
DRUGDOSE	Drug dose (for transmitting doses for pharmacokinetics)
FERT	Fertility
HEM	Hematology (excluding coagulation & differential count)
HLA	HLA tissue typing antigens
MICRO	Microbiology
SERO	Serology (antibodies and most antigens except blood bank and infectious agents)
TCELL	T Cell surface models
TOX	Toxicology
UA	Urinalysis
VIRO	Virology - virus antigens and cultures

Field 10 - Source, is for our internal use, and should be ignored by database users.

Field 11 - EUCLIDES analyte code. The Euclides code identifies the analyte (the first subpart of the first part of the name).

Field 12 - ASTM code. The ASTM codes apply to only a few of the tests (e.g., cell counts, antibiotic sensitivities). These are the codes included in the appendices of HL7 and ASTM E1238-94.

Field 13 - IUPAC code. The IUPAC² code identifies the component, kind of property, and system. Note: Most of the IUPAC codes for chemistry assume the component is measured in substance concentration, e.g., moles, while most U.S. labs report in mass concentration. We have applied the IUPAC code for substance concentration to mass concentration, because IUPAC has no code for the mass concentration variant.

Field 14 - Date last changed.

Field 15 - Reason term was changed. If a term has been changed, the reason for the change

is detailed here.

Field 16 - Change Type Code. DEL = Delete; ADD = add, NAM = change to Analyte/Component (field #2); MAJ = change to name field other than #2 (#3 - #7); MIN = change to field other than those representing the name.

Field 17 - Comments, is for storing free-text comments relating to the test result.

Field 18 - Answerlist, stores the list of answers for results that are reportable from a multiple choice list (e.g., the answers for the term DISPOSITION OF BLOOD PACK are GIVEN;PARTIALLY GIVEN;DISCARDED).

Field 19 - Deprecated or superceded status. Used to mark terms as the database evolves. LOINC codes will not ever be re-used nor will they be removed from the datebase, they will instead by cross-referenced to superceding terms(s) in Field 20.

Field 20 - Map To, is used when a field has been dropped from the active database (by entering "DEL" in the Status field) because it has been replaced by an updated term. In those cases, Map_To contains the LOINC code of the new term that should be used.

Field 21 - Scope

Field 22 - SNOMED code (Future versions)

Field 23 - VA code (Future versions)

Field 24 - MetPath code (for some records). Approximately 1300 terms (mostly chemistry) have been mapped.

Field 25 - HCFA code (Future versions)

Field 26 - CDC Code. Code from CDC Complexity file which maps laboratory tests to the instruments used to perform them. These codes are at the analyte level, not the test instrument level.

Field 27 - Normal Range - Example answers from real tests

Field 28 - Typical units in which the observation is recorded. This field is not yet used.

Field 29 - Units in which Euclides or IUPAC terms are reported (future)

Field 30 - GPI Code. For drugs, this field contains a map to the MediSpan GPI codes, a hierarchical system of classifying pharmaceutical products.

Field 31 - GPI Code Total. For a few products, a simple one-to-one mapping with a GPI code was not possible. In these cases, all applicable GPI codes are contained in this field, separated by semicolons.

Field 32 - Reference. Contains references to medical literature, product announcements, or other written sources of information on the test or measurement described by the LOINC record.

e hope to complete the fields containing new codes, normal ranges, units, examples, answers in the coming year.

Appendix B -- Calculating Mod 10 Check Digits

The algorithm for calculating a Mod 10 check digit is as follows:

Instructions (1) Take the odd digit positions counting from the right (2) Multiply by 2 (3) Take the even digits starting from the right (4) Append these to the front of the results of (2) (5) Add the digits of (4) together (6) Find the next highest multiple of 10 (7) Subtract (5) from (6)		Example 12345 531 1062 42 421062 4+2+1+0+6+2 = 15 20 20 - 15 = 5. Thus, 5 is the Mod 10 check digit for 12345.

[1]. McDonald CJ, Park BH, Blevins L: Grocers, physicians, and electronic data processing. AMA Continuing Medical Education Newsletter 1983; 12(1):5-8.

[2] In the United States, PO (an abbreviation for per ora) is used to identify medications taken by mouth.

[3]. International Union of Pure and Applied Chemistry/International Federation of Clinical Chemistry. The Silver Book: Compendium of terminology and nomenclature of properties in clinical laboratory sciences. Oxford: Blackwell Scientific Publishers, 1995.

[4]. Henry, JB. Clinical Diagnosis and Management by Laboratory Methods. Philadelphia: W.B. Saunders, 1991.

[5]. Burtis CA, Ashwood ER. Tietz Textbook of Clinical Chemistry, 2nd ed. Philadelphia: W.B. Saunders, 1994.

[6]. McDonald CJ, Tierney WM. Computer-stored medical records. JAMA 1988; 259:3433-40.

7. Dick AS, Steen EB (eds). The computer based patient record. Washington DC: National Academy Press, 1991.

[8]. Health Level Seven. An application protocol for electronic data exchange in healthcare environments. Version 2.2 Ann Arbor, MI: Health Level Seven, Inc.; 1994.

[9]. ASTM E1238-94. Standard Specification for Transferring Clinical Observations Between Independent Computer Systems. Philadelphia: American Society for Testing Materials; 1994.

[10]. American College of Pathology. Systematized Nomenclature of Medicine (SNOMED), 2nd edition. Skokie IL: ACP, 1984.

[11]. Euclides Foundation International. EUCLIDES Laboratory Investigation Codes. Available from Dr. Georges DeMoor, Euclides Foundation International nv, Excelsioriaan 4A, B-1930, Zaventern, Belgium. Phone: 32 2 720 90 60.

[12]. Mahon CR, Manuselis G (eds). Textbook of Diagnostic Microbiology. (Philadelphia: W.B. Saunders, 1995)

[13]. Walker RH. American Association of Blood Banks Technical Manual. 11th ed. Bethesda, MD: American Assocation of Blood Banks, 1993.

[14]. Holt JG, Krieg NR, Sneath JT, Williams ST. Bergey's Manual of Determinative Bacteriology. Williams & Wilkins, Baltimore, MD 1994.