Public Health Laboratories and Health System Change . Universal Coding Systems for Clinical Laboratories


The creation of a standardized set of codes to describe laboratory tests and their results is a necessary prerequisite to efficient information exchange, and there have been a number of efforts to establish such codes. While laboratory services have been included in the establishment of general medical standards (e.g., ASTM, SNOMED, HL-7), the logical observation identifier names and codes (LOINC) database merits special mention.

LOINC is a public use set of codes and names for electronic reporting of clinical laboratory results developed by a committee consisting mostly of pathologists and laboratorians representing medical schools and commercial reference laboratories.19   The ultimate aim of LOINC was to create new efficiencies in the reporting of test results across institutions in an era of integration and managed care. The original goal of the committee was to develop a system of codes that would encompass at least 98 percent of the average laboratory's results, and would include an appropriate level of descriptive specificity. Tests that occupied their own columns on a clinical report or had clinical significance distinct from other closely related tests were assigned separate names and codes under the system.

Each test coded under the LOINC system is designated by a long test descriptive code and an associated numerical code. In addition to these descriptive and numerical codes, the LOINC name given to each test is associated with a six part description of the test, which includes the following name fields:

  • Analyte/component name (i.e., what is the test looking for -- potassium, hemoglobin, Hepatitis C antigen)
  • Challenge information (e.g., amount, route and timing of challenges)
  • Special adjustments (e.g., pH)
  • Special distinctions about the relationship of the measured entity to the patient
  • Kind of property measured or observed (e.g., blood product unity, mass, mass concentration, enzyme concentration)
  • Time aspect of measurement or observation (e.g., point observation v. observation integrated over time)
  • System/sample type (e.g., urine, blood, serum)
  • Type of scale of the measurement or observation (e.g., quantitative, semi-quantitative, or qualitative)
  • Type of method used to obtain measurement or observation

To date, LOINC has been used predominantly as a means for communicating laboratory result information among hospitals, commercial laboratories, and providers who use the HL7 system as a convention for transmitting data to and from different computer systems; it has also been widely used throughout the LIS community and has been accepted by the American Clinical Laboratory Association (ACLA) as the recommended standard universal code for submitting laboratory results. Included in the list of institutions currently using LOINC to transmit laboratory data are:

  • MetPath Laboratories
  • Mayo Medical Laboratory
  • ARUP Labs
  • Quest Diagnostics Incorporated
  • Laboratory Corporation of America
  • LifeChem Laboratory Services
  • University of Colorado
  • University of Missouri
  • Indiana University Laboratories
  • Intermountain Healthcare
  • LDS Hospital

The advantage committee members claim LOINC has over other systems for coding laboratory results is its multi-axis approach for identifying laboratory tests. Other laboratory test coding systems (e.g., SNOMED) lack, in some cases, the level of detail necessary in making clinically significant distinctions between the results of similar tests. In addition to the six part name description, the LOINC database contains 23 additional fields, including, among other things, synonymous terms allowing linkage to other systems for coding laboratory results.

While standardization of laboratory test reporting nomenclature through LOINC has been touted for its potential role in helping public health officials work with laboratory data for epidemiological purposes, it has not had an observable effect on computing within PHLs. Of the 46 members of the LOINC Committee, only one represented a state health agency, and an interviewee from the LOINC Committee was unaware of any specific activity linking LOINC to the recovery of utilization data for public health purposes.