Urinary clusterin in chronic nephrotoxicity in the rat.

The excretion of clusterin was compared with that of N-acetyl-beta-glucosaminidase (NAG) in rats given gentamicin daily for 2 months to determine whether clusterin excretion stays elevated after NAG excretion falls during chronic gentamicin administration. Clusterin was measured by radioimmunoassay and NAG by the hydrolysis of 4-methylumbelliferyl-N-acetyl-beta-D-glucosaminide. Gentamicin at 110 mg/kg was given daily for 44 days and thereafter, at 90 mg/kg daily. The excretion rate of both proteins rose rapidly, peaked, and then declined; however, the clusterin values stayed significantly above control values for the entire study, whereas NAG values were close to normal during the last 10 days, even though tubulointerstitial disease was active at that time. For this reason, the further evaluation of clusterin as a marker of renal tubular cell injury or death is warranted.