Detection of rifampicin-induced nephrotoxicity by N-acetyl-3-D-glucosaminidase activity

The objective of the present study was to assess renal damage, if any, by non-invasive technique, viz NAG activity in urine and GFR in patients on continuous and intermittent rifampicin therapy. Eighty-four tuberculosis patients for cross-sectional study and six subjects for longitudinal study on antitubercular therapy and ten patients on withdrawal of rifampicin participated in the investigation; 13 leprosy patients intermittently treated with rifampicin were also included. Twenty-seven normal subjects served as controls. Rifampicin on continuous use resulted in a progressive increase in enzymuria with no change in GFR. An additive toxic effect was obvious in patients receiving streptomycin; when the treatment was withdrawn the urinary NAG activity stabilized within 15-21 days. However, patients receiving rifampicin intermittently did not show any evidence of renal damage. The results suggest that there is a need for monitoring renal damage, particularly on antitubercular therapy, when nephrotoxic agents are administered together.