What is Rheumatoid factor?
Rheumatoid factor is an immunological marker found in a number of diseases including rheumatoid arthritis. Technically speaking, it is an antibody against the Fc portion of IgG (also an antibody). It is detected in the blood.
Rheumatoid factor was found in my blood tests. Does that mean I have rheumatoid arthritis?
No. Rheumatoid factor is not diagnostic of rheumatoid arthritis. Rheumatoid arthritis is diagnosed by the rheumatologist based on the swelling in multiple joints. Rheumatoid factor in found numerous conditions other than rheumatoid arthritis. Moreover, it is also positive in about 5-10% healthy individuals. This is called a false positive rheumatoid factor. Hence, a positive rheumatoid factor alone does not necessarily mean you have rheumatoid arthritis. Please consult a rheumatologist if rheumatoid factor is found in your lab tests. A better test for confirmation of rheumatoid arthritis is anti-CCP antibody.
What is the significance of higher levels of rheumatoid factor?
Higher levels of rheumatoid factor are associated with severe rheumatoid arthritis, more deformities & a higher chance of having Rheumatoid nodules & other extra articular manifestations affecting the eyes, lungs.
Does a negative rheumatoid factor test rule out Rheumatoid Arthritis?
No. A negative rheumatoid factor test does not rule out Rheumatoid Arthritis. It is negative in almost 30-35% patients with Rheumatoid Arthritis.
Does it help in monitoring the severity/ progression of rheumatoid arthitis?
Rheumatoid factor does not help in monitoring the rheumatoid arthritis activity. The same can only be assessed by the number of swollen & tender joints & the DAS score.
Can a positive Rheumatoid factor turn negative later?
Yes. Rheumatoid factor can turn negative. However, this does not mean that Rheumatoid arthritis is in remission. Rheumatoid factor levels do not correlate with Rheumatoid arthritis activity.