I read another great article this week by Dr. Nathan Wei on the usual tests ordered to confirm or monitor the disease of arthritis. The tests he lists are:
ESR (erythrocyte sedimentation rate) which measures inflammation. Naturally someone with active arthritis will have a lot of inflammation, which is what causes the pain. Normal value is 0-15 and when my arthritis was really flaring before I was on a TNF inhibitor it was over 50.
CRP (C-reactive protein) also measures inflammation. Hmmmm – looking at my history I see it got up to 154 – not sure if that is high though – for a reference I have 0-10 but it seems pretty low!
Rheumatoid Factor is positive in about 70-75% of patients with rheumatoid arthritis. I had the test twice in 2004 and once in 2007, and it was negative in all cases.
Anti-CCP is apparently more specific than Rheumatoid Factor and if positive early in the disease may indicate a more aggressive arthritis. I’ve never had this test.
ANA is useful for testing for lupus. Patients who test negative for ANA are 99% certain not to have lupus. However apparently 30% of healthy people will test positive. So I guess ANA is perhaps useful for showing if someone is more likely to have an autoimmune condition. As Dr. Wei notes, if it is positive then it indicates to doctors to test further. My ANA was negative twice in 2004, and positive in 2007.