9.3 LOINC Parts and Part hierarchies

In order to support several key aspects of development, Regenstrief has created LOINC Parts, which are a coded representation of a value for a dimension used to specify a LOINC concept. LOINC Parts support the translation of LOINC terms into other languages, easy linking of synonyms across many terms, the creation of hierarchies to group related LOINC terms, and several other functions.

Individual LOINC Parts are assigned a non-semantic identifier with a LP prefix and a mod-10 check digit.

The intended use of the LOINC Parts and LOINC Part hierarchies are to organize or be constituents of LOINC terms. As described in the LOINC license, they are not intended for use as a “standalone” terminology nor apart from LOINC terms.

Furthermore, LOINC Parts and LOINC Part hierarchies are not strictly managed under the same policies (e.g. concept orientation, concept permanence) as are LOINC terms.

9.3.1 Part content in the LOINC distribution

Beginning with LOINC version 2.61, we included a Part artifact within the primary LOINC download file. This file includes three tables: one includes all of the Parts associated with all of the LOINC terms in the current release, the second contains links between LOINC terms and their parts, and the third has mappings between a subset of Parts and related codes from external standard terminologies such as SNOMED CT. Please see the PartFile_Readme.txt document included in the PartFile (located in AccessoryFiles for more information.

LOINC Part information can also be obtained programmatically using the LOINC Terminology Service using HL7 FHIR.

Furthermore, LOINC Parts can be identified quickly using the SearchLOINC web app. Simply change the search scope to Parts and enter your query.

9.3.2 Part linkages

Parts provide a means of connecting data including to external ontologies. For more information, see the dedicated section within this documentation.

9.3.3 Example of a LOINC and its composite Parts

The following tables show how the LOINC term and its corresponding Parts are represented in the three CSV files available within this artifact.

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Excerpt from LoincPartLink.csv file:

Excerpt from Part.csv file:

Excerpt from PartRelatedCodeMapping.csv file: