# Immunoassay vs Radioimmunoassay

**URL:** <https://forum.loinc.org/t/immunoassay-vs-radioimmunoassay/1986>\
**Category:** General\
**Created:** [June 18, 2024, 1:22am UTC](https://forum.loinc.org/t/immunoassay-vs-radioimmunoassay/1986 "2024-06-18T01:22:31Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![therqeb](https://forum.loinc.org/letter_avatar_proxy/v4/letter/t/a87d85/32.png) [@therqeb](https://forum.loinc.org/u/therqeb)\
**Post date:** [June 18, 2024, 1:22am UTC](https://forum.loinc.org/t/immunoassay-vs-radioimmunoassay/1986/1 "2024-06-18T01:22:31Z")

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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](https://loinc.org/LP217198-3/)) 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](https://loinc.org/LP217197-5/)) 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.

Thanks

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**Author:** ![pdbanning](https://forum.loinc.org/letter_avatar_proxy/v4/letter/p/9f8e36/32.png) [@pdbanning](https://forum.loinc.org/u/pdbanning)\
**Post date:** [July 11, 2024, 6:15pm UTC](https://forum.loinc.org/t/immunoassay-vs-radioimmunoassay/1986/2 "2024-07-11T18:15:31Z")

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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,  
Pam

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**Author:** ![therqeb](https://forum.loinc.org/letter_avatar_proxy/v4/letter/t/a87d85/32.png) [@therqeb](https://forum.loinc.org/u/therqeb)\
**Post date:** [July 11, 2024, 6:35pm UTC](https://forum.loinc.org/t/immunoassay-vs-radioimmunoassay/1986/3 "2024-07-11T18:35:19Z")

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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,

Devin