Urinary γ-glutamyl transpeptidase activity in dogs with gentamicin-induced nephrotoxicity

SUMMARY Serum creatinine concentrations, 24-hour endogenous creatinine clearance, and 24-hour urinary γ-glutamyl transpeptidase (uggt) activity were measured daily in 6 dogs given nephrotoxic dosages of gentamicin (10 mg/kg of body weight) every 8 hours for 10 days. Mean uggt activity was significantly increased by day 5 (P < 0.05) and preceded significant increases in serum creatinine values (> 2.0 mg/dl) observed on day 9. Endogenous creatinine clearance remained within normal limits (2.98 ± 0.96 ml/min/kg) until day 8. Urinalyses performed 8 days after initiation of gentamicin treatment indicated renal tubular damage (granular casts) in 1 of the 6 dogs, and glucosuria in 3 of the 6 dogs. Measurement of uggt activity was a more sensitive and reliable method of assessing acute renal tubular damage induced by gentamicin than were serum creatinine concentrations or 24-hour endogenous creatinine clearance.