Rheumatoid Factor (Rf) IgA IgG IgM
Rheumatoid Factor (Rf) IgA IgG IgM
The concentration of RF tends to be highest when the disease peaks and tends to decrease during prolonged remission. Increased RF levels may also accompany a variety of acute immune responses, particularly viral infections and a number of liver diseases (infectious mononucleosis, tuberculosis, leprosy, various parasitic diseases, liver disease, sarcoidosis, and systemic lupus erythematosus).