The significance of enzymuria in assessing the nephrotoxicity of cisplatin in a total dose of 100 mg/m 2 or iphosphamide in a total dose of 9 g/m 2 for children with solid malignant tumors (10 and 9 patients, respectively) was studied. Chemotherapy caused stable hyperenzymuria consisting in a significant increase in N-acetyl-lS-D-hexosaminidase, 7-glutamyltransferase, and alanine aminopeptidase activities in the urine during chelnotherapy in comparison with the initial values. The levels of enzyme excretion with the urine were higher in patients treated with iphosphamide than in those treated with cisplatin. The increase in serum creatinine and urea concentrations vs. the age-specific noru~ was obsen,ed in only 2 out of 9 children treated with iphosphamide. These results permit considering enzymuria as the most sensitive method for the diagnosis of nephrotoxicity. Key Words: chemotherapy; nephrotoxicity; urine enzymesThe therapeutic effect of antitumor drugs is often associated with toxic effects on various organs and systems. Nephrotoxicity characteristic of the platinum preparations, iphosphamide, and other cytostatics is a complication limiting the drug dose. Biochemical parameters routinely used for the diagnosis of toxic involvement of the kidneys, primarily nitrogen-containing serum compounds urea and creatinine, are not vein informative. Measurements of the urinary enzymes have been recently used for the diagnosis of renal involvement caused by toxic effects of antitumor, antibacterial, and other drugs [1,6,8,10]. Biochemical analysis of urine for early detection of nephrotoxicity of antitumor therapy is particularly ilnpoJtant in pediatric oncology, since the proposed method is noninvasive. The aim of this study was to assess the significance of biochemical parametel~ of blood serum and urine for timely diagnosis of nephrotoxicity in children with solid tumors receiving chelnotherapy. MATERIALS AND METHODSThe nephrotoxicity of chemotherapy protocols including iphosphalnide and cisplatin has been assessed by biochemical analysis of the blood and urine in :19 children (10 boys and 9 girls) aged 5-16 yeal~ before, during, and after chemotherapy. The children were followedup from 2 weeks to 3 months, during this period they were administered 1-3 5-day courses at 3-4-week hltervals. Nine children with nephroblastoma relapses (n=3), nephroblastoma (n=2), rhabdonayosarcoma (n=3), and disseminated Ewing's sarcoma (n=l) were treated by iphosphalnide-based protocols including iphosphamide in a total dose of 9 g/m 2 per course, vepeside (500 rag/m2), and carboplatin (450 1rig/m2). Ten children with osteogenic sarcoma (n=4)