Effects of ischemia on human renal interstitial fluid metabolites

Microdialysis is a technique for monitoring the concentration of molecules in the interstitial fluid of living tissue. We report the effects of ischemia on human renal interstitial fluid molecules.

Ten patients with a renal mass or upper tract transitional cell carcinoma who elected laparoscopic nephrectomy or nephroureterectomy were studied with in situ renal microdialysis. Microdialysate was continuously collected into separate vials every 10 minutes before and after the renal artery was stapled. Samples were analyzed for the glucose, pyruvate, lactate and glycerol concentration.

The concentration of all 4 molecules was stable throughout the pre-ischemia baseline period. Glucose and pyruvate concentrations decreased to almost zero during the first 60 minutes of ischemia. Lactate increased during the initial 60 minutes of ischemia and then plateaued with continued ischemia. The glycerol concentration increased directly throughout the ischemia time.

The trends of human interstitial metabolite concentrations during ischemia are similar to trends found in the porcine model. The human renal interstitial glycerol concentration increases directly throughout the duration of ischemia and serves as a marker of nephron damage. Microdialysis is a tool that provides real-time, renal unit specific, minimally invasive data on the metabolic status of the human kidney during ischemia. It may be helpful for avoiding permanent renal ischemic injury.