Assessment of beta-2-microglobulin concentration in serum and urine in rheumatoid arthritis.

Assessment of beta-2-microglobulin (beta-2-M) concentration in serum and urine was made in 50 patients with rheumatoid arthritis (RA). The most often noticed pathology was proteinuria. We observed a significant increase of beta-2-M concentration in serum of patients without rheumatoid factor and in patients with proteinuria. In all patients the concentration of beta-2-M in urine was significantly higher than in the controls. We did not observe any influence after treatment on beta-2-M concentration. The increase of the concentration of beta-2-M may be a marker for the early damage of kidney in RA.