[Biochemical tests in the diagnosis of nephrotoxicity: assessment of the significance].

In order to identify early signs of nephrotoxicity in 38 patients with malignant tumors of the testicle, the data of 3 biochemical tests (measurements of gamma-glutamyltranspeptidase (gamma-GT) activity in the urine, of the content of creatinine and urea in blood serum) were compared. Activation of gamma-GT in the urine may be viewed as the first and early sign of nephrotoxicity, since the rise of creatinine and urea in the blood was observed later. The magnitude of gamma-GT activity (means + 2 sigma) - 5.9 Units/mmo le Cr may provide basis for the judgement about nephrotoxicity according to the scheme applied. The fall of gamma-GT activity without any further increase after multiple courses of chemotherapy is of prognostic significance for its evidences profound injury to the renal parenchyma and may serve as basis for correcting the doses of chemotherapeutic drugs. The reduction of gamma-GT activity to less than 3 Units/mmole creatinine (means - 2 sigma) may be regarded as indication for instituting disintoxication therapy.