LOINC Parts are coded representations of the attribute values that combine to create a LOINC term. 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.

The LOINC Parts and Part hierarchies are only intended to be constituents of and/or organize LOINC terms. As described in the LOINC license, they are not intended for use as a “standalone” terminology apart from LOINC terms.

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

For more information regarding LOINC Parts, see Section 9.3 ("LOINC Parts and Part hierarchies") of the LOINC Users' Guide.

TIP Part codes have a prefix of LP

Part.csv

This file contains all of the primary LOINC Parts that are associated with any of the LOINC terms included in the current LOINC release. The types of Parts included in this file fall into five major categories. For definitions of each Part in the first four categories, see the chapter of the LOINC Users' Guide indicated below for each category.

1. Six major Parts that define a LOINC term (Component, Property, Time Aspect, System, Scale, and Method)
   • Section 2 "Major Parts of a test or observation name"
2. Additional Parts that contribute to the term, such as the Divisor, Challenge, and Class
   • Section 2 "Major Parts of a test or observation name"
3. Parts that define document terms within the Document Ontology
   • Section 6 "LOINC Document Ontology"
4. Parts that define radiology terms according to the LOINC/RSNA Radiology Playbook unified model
   • LOINC Users' Guide Annex ("LOINC/RSNA Radiology Playbook User Guide")
5. Parts that are used in the LoincPartLink file but are not part of LOINC's official semantic model. These Parts may later be used to link to external sources or coding systems. Currently the only Part type that falls in this category is Gene.

Parts that were previously released but that are no longer used to define any published LOINC term are not included in this file. However, Parts associated with Deprecated LOINC terms ARE included in this file, because those terms continue to be released.

You will notice that in some cases, especially in the radiology domain, Parts may appear incomplete, such as LP234153-7, which is the Component (Views AP + odontoid) + (View lateral. This Part, and others like it, are not erroneous. Rather, they are necessary for our internal processes that build the LOINC Long Common Name from the individual parts.

PartRelatedCodeMapping.csv

This file contains mappings between LOINC Parts and concepts in external coding systems, such as SNOMED CT and RadLex. Only the subset of LOINC Parts that are mapped to an external concept are included in this file. The MapType and ContentOrigin fields are only valued for a subset of mappings. For the SNOMED CT mappings, the values in both of these fields are based on similar content in the LOINC/SNOMED CT Map Set published jointly by Regenstrief Institute and SNOMED International.