Representing Laboratory Tests

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Type Standard / Implementation Specification Standards Process Maturity Implementation Maturity Adoption Level Federally required Cost Test Tool Availability
Standard for observations
Rating 3
Standard for observation values
Rating 1
Limitations, Dependencies, and Preconditions for Consideration Applicable Value Set(s) and Starter Set(s)
  • Laboratory test and observation work in conjunction with values or results which can be answered numerically or categorically.  If the value/result/answer to a laboratory test and observation is categorical that answer should be represented with the SNOMED CT® terminology. 
  • A single lab test with a single result will have the same LOINC® term for its order and result answer, but a panel order will have an order LOINC® term and multiple result LOINC® terms for each result in the panel. 
  • A single lab test with a single result may have the same LOINC® code for the order and the result or may have a more specific code in the result (for example if the order code was method less or did not declare the system property). A panel order will have an order LOINC® code and multiple result LOINC® terms for each result in the panel.  
  • Guidance is available for using SNOMED CT® and LOINC® together.
  • See LOINC projects in the Interoperability Proving Ground.
  • For more information about observations and observation values, see Appendix III for an informational resource developed by the Health IT Standards Committee. 


On behalf of American…

On behalf of American Medical Association (AMA) I appreciate the ability to comment on the 2017 Interoperability Standards Advisory.

The AMA requests that the Current Procedural Terminology (CPT) code set be added to the standards listed in I-I: Lab Tests – Interoperability Need: Representing Laboratory Tests.  The CPT code set contains a comprehensive and regularly curated list of laboratory tests and nomenclature.  Of particular note are the Multianalyte Assay with Algorithmic Analyses (MAAA) codes, Molecular Pathology Tier 1 and Tier 2 codes, and the new Proprietary Laboratory Analyses (PLA) section of CPT.  The Molecular Pathology section addresses a growing need to identify specific laboratory procedures involving the analyses of nucleic acid to detect variants in genes.  The PLA section identifies clinical diagnostic laboratory tests (CDLTs), as well as tests that CMS designates as advanced diagnostic laboratory tests (ADLTs).  The PLA section is designed to include the full range of medical laboratory tests including, but not limited to, MAAA and Genomic Sequencing Procedures.  CPT has a high level of maturity for its development process and implementation, and is the most widely adopted outpatient procedure code set.  It is also federally required.

LOINC is absolutely right…

LOINC is absolutely right for coding tests. CPT is OK, but lacks the specificity that LOINC has.

SNOMED CT is good for microbacterial susceptibility, and certain other kinds of values, but that needs more clarity in the ISA.

UCUM should be considered for units.

We strongly concur with the…

We strongly concur with the listing of LOINC and SNOMED CT for this interoperability need, and is the solution being used successfully in many countries. 

Concur it is the right thing…

Concur it is the right thing to do. Be careful about using more than one coding system for a given purpose because it will thwart interoperability.  Believe that the NCVHS is taking a position of one code system for one purpose. 

From one HIE integrator, we…

From one HIE integrator, we get a figure of 50% of lab tests coming across with LOINC codes. The large referral labs have LOINC codes for 99%+ of their unique codes and they represent about 45% of the nation's test results. Think 50% might be a fair estimate. If so, think it deserves higher than a 3+.

The % of ordinal values with SNOMED codes are small, <5%.


consider the following text for Preconditions for Consideration section

Guidance exists for using SNOMED CT and LOINC together (link to guidance is



adoption of SNOMED CT is 1 dot.