Study Objective: To examine the effects of hydroxyethyl starch (HES) on renal function.

Design: Randomized, controlled trial.

Setting: Operating theatre of a university hospital.

Patients: 60 ASA physical status I and II male patients undergoing middle ear surgery.

Interventions: Patients received either lactated Ringer’s solution (LRS) or one of three HES solutions. The HES solutions were administered in a dose of 15 mL/kg bodyweight (bw), the Ringer’s solution in a dose of 60 mL/kg bw, after induction of anesthesia over a period of one hour.

Measurements: Blood and urine samples for hormone and enzyme tests were obtained at defined times before, during, and after surgery. Urine excretion, glomerular filtration rate (GFR), renal plasma flow, and routine hemodynamic parameters were measured simultaneously.

Main Results: There were no significant intergroup differences regarding GFR, renal plasma flow, or tubular and glomerular integrity as measured by specific proteins and enzymes (⍺-1-microglobulin, Tamm-Horsfall-protein, immunoglobulin G, and N-acetyl-β-D-glucosaminidase). Arginine vasopressin decreased in all groups during and following anesthesia, aldosterone and plasma renin activity decreased only in the HES groups, and angiotensin II decreased only in the HES 200/0.5 group. Central venous pressure increased during fluid administration in the LRS group and returned to baseline sooner in the HES groups.

Conclusions: Hydroxyethyl starch administration appears to be risk-free with regard to renal function in patients without preexisting renal dysfunction who undergo general anesthesia. The relevance of the decrease in aldosterone following HES therapy needs further investigation.