Expanded Set of Draft LOINC-SNOMED CT Mappings and Expression Associations Now Available

The Regenstrief Institute and IHTSDO are very pleased to announce that the September 2015 LOINC - SNOMED CT Expression Association and Map Sets - Technology Preview is now available.

The draft file (called a Technology Preview in SNOMED CT lingo) is now available.

You can download the file here.

The Technology Preview files were generated as part of the cooperative agreement signed between the Regenstrief Institute and the IHTSDO in July 2013. (Read more about the collaboration).

The agreement details how SNOMED CT and LOINC will be linked through:

  1. a map of LOINC terms to post-coordinated SNOMED CT expressions
  2. a map of LOINC parts to SNOMED concepts
  3. a map between LOINC terms and existing pre-coordinated SNOMED concepts
  4. LOINC Answer sets mapped to SNOMED codes; and
  5. addition of new content in either terminology.
This Technology Preview (draft mapping) is based on the July 2015 IHTSDO International release of SNOMED and the December 2014 version 2.50 LOINC release. The Technology Preview contains two main sets.
The first is the LOINC Term to SNOMED Expression Reference Set. The LOINC Term to SNOMED Expression Reference Set contains 14736 active LOINC
Terms associated with post-coordinated SNOMED CT expressions. This set covers approximately 75% of the LOINC Top 2000 content.
The second is the LOINC Part to SNOMED Reference Set that consists of 4061 LOINC Parts (LP) mapped to one or more SNOMED concepts.

This Technology Preview is available in three formats: RF2, OWL, and human readable. The human-readable format includes artifacts related to items 1 and 5 above, and the RF2 and OWL formats contain artifacts related to items 1, 2 and 5 above.

RF2 Format

The RF2 package contains two content files: a LOINC Term to SNOMED Expression Reference Set and a LOINC Part to SNOMED Reference Set. For each reference set it contains a full release file, a snapshot file and an (empty) delta file.

OWL Format

The OWL package is for reviewing and classifying the content with ontology viewing/editing software such as Protege. This is not an official IHTSDO release format and does not contain metadata such as refset identifier or correlation designation.

Human Readable (Excel) Format

The human readable package contains an Excel spreadsheet for reviewing the map of LOINC Terms to SNOMED CT expressions in a human-readable tabular format. This is not an official IHTSDO release format. It does not show the nesting of the content. The map from LOINC Parts to SNOMED CT concepts is not included in this version because the LOINC Parts are not independently available for public release.

Provide your feedback now

Feedback is requested on the Technology Preview release to inform future development and determine fitness for purpose. Feedback on the formatting of expressions, maps and reference sets is expected; feedback on the content of the expressions or mapping themselves is also welcome. The IHTSDO requests that you please provide feedback by 16 November 2015 using the online form.


The Technology Preview is distributed for evaluation purposes only. It is not for use in production clinical systems or  in clinical settings. USE WITHIN CLINICAL SYSTEMS CANNOT BE SUPPORTED AT THIS TIME.