Flow Cytometry - CD19 cells per 100 Lymphocytes = /100 cells?

I hope someone can help a confused respiratory therapist out.

I’m trying to assign a LOINC code in our system for a flow cytometry test that measures CD19 cells per 100 lymphocytes in blood specimen.

The reference lab has assigned 8117-4 Cells.CD19/100 cells:NFr:Pt:Bld:Qn based on a related name in the LOINC details page of B cells expressing CD19 as a percent of total lymphocytes.

I see LOINC 97597-9 Cells.CD19/100 lymphocytes:NFr:Pt:Respiratory system specimen.lower:Qn:Flow cytometry.

There are many LOINCs for other cell types/100 Lymphocytes in bld.

Why is there no Cells.CD19/100 lymphocytes in blood?

The web-based Knowledge base is significantly more difficult to find what I’m looking for compared to the downloadable LOINC User Guide.

I think I found my answer, though the imprecision hurts my programmer brain. I’ll just have to remember that /100 cells sometimes means /100 leukocytes and sometimes means per cells containing the marker and sometimes means something else based on the clinical context.

That’s one of the things that makes LOINC so hard. It’s both too precise (especially with regard to the system axis) and imprecise. I won’t even mention how much the basic premise of a 6-axis data model expressed in a single code hurts my brain. :slightly_smiling_face:

Hi Doug, thank you for comments. I cannot speak to the clinical concepts, but as a developer, I absolutely agree regarding the issues with the online Knowledge Base. We have plans to overhaul the organization of the documentation. This should allow items to be more easily found via search. I do not yet have a timetable for this work.

Hi Doug! Thank you for the question. I will have the Lab LOINC committee review this part of the knowledge base; I know I personally haven’t been using /100 cells in this manner. And cudos to a respiratory therapist background performing LOINC mapping! You must really like puzzles too!.

Hi Doug! The Lab LOINC committee met this past Thursday and agreed there should be LOINCs issued for cell markers measured by 100 of a particular cell type. The database grows by volunteer submissions. Evidently no one else has thought (or had time) to submit for CD19+/100 Lymphocytes. Please email me at pdbanning@solventum.com and I will help get the submission made. Thank you!

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