[Diagnosis of rheumatoid arthritis--using biochemical technique]

Rheumatoid arthritis is a systemic disease. Onset of the disease occurs most often between the ages of 20 and 60 years with a peak at 30 and 50 years. The diagnosis of rheumatoid arthritis (RA) is usually based on the revised criteria for the classification of RA. The presence of 4 or more of 7 criteria defines "rheumatoid arthritis". There is today much interest in development of a biochemical "marker" of RA, to detect the early phase of RA. Some approach employs measurement of serum and joint fluid levels of articular cartilage macromolecules, antibodies, and so on. In the section, we would like to describe some materials available now. It is difficult to point out a single material superior to rheumatoid factor to make a diagnosis of RA at the present time.