Renal disease associated with rheumatoid arthritis rationale of urinary N-Acetyl-B- glucosaminidase and B2-microglobulin analysis

ABSTRACT

N-Acetyl-B-D-glucosasminidase [NAG] and B2-microglobulin [B2-MG] are measures of tubular injury, representing abnormalities of different processes involving the renal tubules. When the urinary excretion of these 2 proteins were studied in 32 patients with rheumatoid arthritis and 10 healthy control subjects, a significantly increased excretion of NAG/mg creatinine [p < 0.01] and b2-mg/mg creatinine [p < 0.001] was observed in patients compared to the controls. Patients with active disease had insignificantly higher levels of excreted proteins. Despite the lack of correlation between NAG/creatinine and B2-MG/creatinine with indices of disease activity, the frequency of abnormal excretions of the 2 proteins were higher in patients with active disease. Patients treated with nonsteroidal anti-inflammatory drugs [NSAIDs] had higher NAG/creatinine and B2MG/creatinine than those treated with a combination of NSAIDs and steroids. These findings suggest that the renal affection associated with rheumatoid arthritis is bifactorial from the intrinsic effect of the disease as well as the nephrotoxic action of NSAIDs. Inclusion of at least NAG/creatinine excretion to the routine urinalysis would be beneficial to the patients