[Clinical significance of microalbuminuria in patients with rheumatoid arthritis]

In order to make an estimate of clinical significance of microalbuminuria (MAU) in patients with rheumatoid arthritis (RA), we studied MAU in 138 patients with RA without macroalbuminuria. MAU was assayed by double-antibody RIA in the ambulatory urine. Moreover, urinary (U) beta 2-microglobulin (BMG) and N-acetyl-beta-D-glucosaminidase (NAG) were simultaneously measured. The values for MAU/U-creatinine (U-Alb index) in patients with RA, osteoarthropathy (OA) and normal controls were 25.7 +/- 38.2, 11.4 +/- 11.5 and 7.7 +/- 3.5, respectively, and U-Alb indices in patients with RA were significantly higher than U-Alb indices in patients with OA and normal controls. Especially, in patients with RA receiving lovenzarit disodium and gold sodium thiomalate (GST), U-Alb indices were elevated. U-Alb indices were not correlated with clinical findings in RA. Also, U-Alb indices were not correlated with U-BMG indices and U-NAG indices in patients with RA. In serial measurements of U-Alb index, U-BMG index and U-NAG index in a patient with RA who developed massive macroalbuminuria during GST therapy, it was found that U-Alb index was elevated first, followed by U-NAG index and finally U-BMG index was elevated. These results indicate that U-Alb indices are elevated in patients with RA without macroalbuminuria, and serial measurements of MAU in patients with RA, especially receiving disease modifying antirheumatic drugs, are useful for the detection of subclinical glomerular injury.