my5oh t1_iu6o2ts wrote on October 28, 2022 at 11:24 PM

Reply to comment by perrumpo in Newly discovered species of bacteria in the microbiome may be a culprit behind rheumatoid arthritis by geoxol

I said often, I did not say exclusively in psoriasis patients. And there was never a rheumatoid factor test. Your doctor may call it that, but they are testing for the inflammatory markers. I have RA and have been on Humira for it for a couple years now. And I wasn’t talking about how to diagnose, I was adding to the point that you can show negative but still be diagnosed with something. And that it has an actual name, not just a misdiagnosis for another form of arthritis.

perrumpo t1_iu6qowa wrote on October 28, 2022 at 11:45 PM

Sure, but I wanted to clarify for anyone reading the comments that you can have psoriatic arthritis without psoriasis. That is part of what makes PsA hard to diagnose and to distinguish from RA.

I believe you that there are tests for inflammatory markers, but there are also antibody tests, including RF. Here is a quote from rheumatoidarthritis.org:

> “In most cases of rheumatoid arthritis, the patient tests positive for rheumatoid factor (RF) and/or anti-citrullinated peptides (CPP) antibodies.”

They have a whole page about the RF blood test, so I don’t know what else to tell you. I’m not a physician.