System type for Micro Antibody tests

We have been assisting implementersin mapping to the LOINC standard and have noticed that many of the Micro antibody tests indicated the specimen (system) type as serum. Their analyzers use plasma for many of these tests. Should we be submitting a formal request to have them changed from serum to Ser/Plas to reflect today’s testing methods? Is this already being addressed?


Yes, we welcome a formal request for updating Systems from Ser or Plas to Ser/Plas. Updates to LOINC terms can be made through the website at Request Changes to Existing LOINC Content – LOINC. Please provide documentation to support the update request.

FYI from Page 28 of the LOINC Users’ Guide:

For many types of tests, the distinction between plasma and serum is irrelevant. When testing on serum or plasma is clinically equivalent, the System should be recorded as Ser/Plas, meaning “either Serum or Plasma”. Note that the use of a LOINC code with Ser/Plas as the System to report the result of a specific manufacturer’s assay does not imply that the given assay is approved for use with both serum and plasma specimens; it simply means that the results obtained from testing serum and plasma are clinically equivalent, independent of which assay was used. Sometimes the test can only be run on either plasma or serum; the Component will then be associated with either Ser or Plas in one observation. If the test can be run on either but the results are clinically different and standardized (a very rare circumstance), two separate tests will be defined in our file, one with a System Plas and one with a System Ser. The current LOINC database includes some Ser tests and some Plas tests that should really be Ser/Plas. As we determine that a Ser or Plas test really should have been designated Ser/ Plas, we will change the designation.

Thank you!
Jami Deckard
LOINC Content Developer

See here: <a href=“”>;/a&gt;