Use of urinary enzymes as markers of nephrotoxicity

Urinary excretion of enzymes can be monitored continuously at low cost, with commonly available laboratory equipment; there is little discomfort for the animal or person investigated. Under controlled conditions, the time-course and dose-dependence of some pathophysiological events in the kidney can be followed by measuring urinary enzymes. The activities of enzymes in urine are, however, affected by a large number of parameters, even under physiological conditions. Furthermore, the heterogeneity of the kidney renders application of urinary enzymes for diagnostic purposes difficult. Assessment of renal injury by urinary analysis may be possible only if the pathophysiological mechanisms and the time sequence of the nephrotoxicity are known.