Monitoring of chemotherapy-induced proteinuria using capillary zone electrophoresis

Capillary zone electrophoresis (CZE) was investigated for its suitability to monitor proteinuria occurring during nephrotoxic drug therapy. Urine samples of tumor patients receiving chemotherapy consisting of carboplatin, etoposide, and ifosfamide were concentrated and desalted in microconcentrators and analyzed in two different alkaline CZE buffer systems. Reduction of electroosmotic flow (EOF) by the addition of putrescine increased the number of resolved protein peaks. Both CZE methods were linear between 2.5 and 50 μg/ml, exhibited satisfactory precision (relative standard deviation <10%) and were suitable for monitor the time course of proteinuria after chemotherapy administration. In contrast to sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE), CZE detected interindividual differences in protein patterns. Whereas these differences hampered a direct quantification of proteins in urine, they may contain information on the type or extent of kidney damage.