In order to determine the relationship between the nephrotoxicity of acetaminophen and urinary gamma-glutamyl transferase (GGT) excretion, a single dose of 900 mg/kg acetaminophen (APAP) was administered to rats intraperitoneally. Following drug administration, 24 hour urine was collected and the kidneys were removed under ether anesthesia for histological examination. GGT activity measurements and quantitative analysis for creatinine was carried out on urine samples. Urinary GGT activity in the APAP administered group (n=12) (1.88 ± 0.21 U/mg creatinine) was significantly higher than in the control group (n=16) (0.77 ± 0.05 U/mg creatinine) (p<0.0002). Histological examination of the kidneys under light microscopy showed only very slight tissue damage. Further use of urinary GGT activity measurements in experimental nephrotoxicity studies has been suggested.

Cathepsin D activity has been studied by a fluoremetric assay in the urine of acute post-streptococcal glomerulonephritic (APSGN) patients aged from 3 to 14 years and has been found elevated when compared with four groups of controls. This activity cannot be accounted for by erythrocytes and/or leukocytes in the urine of these patients since haematuric and pyuric controls did not exhibit an amount of enzyme activity greater than the normal control group. Cathepsin D activity can be attributed to lysosomal enzymes released from polymorphonuclear leukocytes which are in close contact with glomerular basement membrane. Complement C3 levels in serum and cathepsin D activity in urine of these patients showed no correlation.

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