Hello @margarita514, welcome to Connect. I'm tagging our moderator @ethanmcconkey to see if we should move your post to the following discussion where it will receive more visibility and you can meet others who share your symptoms.

> Groups > Autoimmune Diseases > Rheumatoid Arthritis (RA) - Introduce yourself and meet others
-- https://connect.mayoclinic.org/discussion/rheumatoid-arthritis-ra-introduce-yourself-and-meet-others/

I did find an article that discusses your question on interference in immunoassay that you might be interested in.

How to Detect and Solve Immunoassay Interference
-- https://www.aacc.org/publications/cln/articles/2015/october/how-to-detect-and-solve-immunoassay-interference