From STU 1 to STU 2, the Tumor Marker Test ValueSet advanced from being an enumerated list of LOINC terms to a collection of LOINCs defined by Component LOINC Parts (LPs). In general, we are supportive of this intensional definition approach as it is more likely to capture new codes in subsequent LOINC releases.(Daniel Vreeman) However, by using only Component LPs, the ValueSet includes extraneous terms. For example, the ValueSet includes LOINCs with a Component of LP14329-4 Choriogonadotropin.beta subunit, and therefore the expansion inadvertently includes prenatal tests like 19175-9 Choriogonadotropin.beta subunit [Moles/volume] in Amniotic fluid, which are not tumor marker tests. Using LOINC System LPs, and other LOINC Part types, to further refine this value set would result in a more concise and accurate set.

In a related implementation guide (not yet targeted for HL7 balloting), we have constructed a collection of ValueSets in this more refined approach for a superset of the mCODE tumor marker tests. You can review those ValueSets here: https://simplifier.net/guide/LabDatafromEHRstoRegistrieswithFHIR/TerminologyValueSets

In addition, we suggest that constructing separate ValueSets per test type is a more helpful approach for both implementers and ValueSet maintainers. We suggest then transforming this ValueSet http://hl7.org/fhir/us/mcode/ValueSet/mcode-tumor-marker-test-vs into a parent set whose definition is made up of the inclusion of the each sub-valueset per test type.