Urinary LDH-release for evaluation of postischemic renal function.

Following renal ischemia under protection, the perfusion of the tubular system increases concomitant to the rise of GFR. The transport into urine of enzymes entering the tubular lumen due to ischemic injury is dependent on tubular flow. Thus, we examined if in the early postischemic phase urinary enzyme determinations can contribute to the evaluation of the ischemic injury despite the interference of a changing tubular washout. Canine kidneys were perfused with different protective solutions and subsequently rendered ischemic. From the beginning of reperfusion the endogenous creatinine clearance, the urine minute volume and the urinary LDH-concentration were determined. The urinary LDH-concentration allowed only a rough assessment of renal ischemic damage. The adjustment of the urinary LDH amounts to the GFR resulted in a better graduation according to the ischemic stress. With such a standardized LDH parameter the urinary LDH release was somewhat lower on the average when L-aspartate was added to the HTK solution in place of chloride. In conclusion, during the early postischemic recovery after renal protection the examination of the urinary enzyme release may be a useful diagnostic means for the assessment of the extent of the ischemic injury if an appropriate frame of reference is applied.