2025-12-19:
LOINC uses DIRECT SITE = Specimen when their system is unspecified (i.e. XXX). There is no corresponding SNOMED concept for the NPU System which can be “any part of the universe”.
That leaves two alternatives:
- INHERES IN = SNOMED CT concept 138875005 |SNOMED CT Concept (SNOMED RT+CTV3)|
- to leave the relationship out