Immunoassay vs Radioimmunoassay

I am trying to figure out if observations using an Radioimmunoassay methodology are always listed as ‘by radioimmunoassay’ or if they can be listed as ‘by immunoassay’.

The IA.rapid LOINC part page (LOINC Part LP217198-3 IA.rapid) lists some methodologies that are specifically under the immunoassay umbrella and some that specifically are not, but radioimmunoassay is not mentioned either way. The IA LOINC part page (LOINC Part LP217197-5 IA) provides no further description of IA and no explanation of what methodologies do or do not fall under the IA umbrella (as an aside, it seems a bit odd this is mentioned on the IA.rapid page but not the IA page). The RIA LOINC part page also provides no additional information.

There are a handful of observations that have radioimmunoassay listed as a method. If RIA and IA are treated as separate methods in LOINC, there are some analytes that I would expect to see have an observation with RIA as the method. For example, thyroxine and free thyroxine.

I don’t know if I am not seeing these observations because 1) IA actually includes RIA in LOINC, 2) the particular RIA observations I am interested in have not been added to LOINC.

As for a little bit of context, both T4, FT4, and some other thyroid hormone lab tests are often analyzed using RIA in veterinary medicine, which is why I am looking for these observations.


1 Like

Hi Devin and Welcome!
Apologies for delayed reply. The Lab Committee is taking a few month hiatus. As I recall once the RIA method came around there was concern about getting too granular and moving development more towards immunoassay as the overarching umbrella. I will mark this as a discussion topic with the LOINC director after the August release comes out. More to come!
Best regards,

1 Like

Hi Pam,
Thank you for your reply. I completely understand that the August release is the top priority right now. I look forward to any additional information that can be provided in August.

Thanks again,