Glomerular hyperfiltration after unilateral nephrectomy in living kidney donors

Abstract

Glomerular hyperfiltration, which is expected to occur after uninephrectomy, could potentially damage the non-transplanted donor kidney in living donor transplantation. We therefore prospectively measured renal function (inulin and PAH clearance), albumin excretion and blood pressure in the donors of 30 consecutive living donor kidney transplants before uninephrectomy (n = 29) and 1 week (n = 27) and 1 year (n = 16) after. Hyperfiltration was defined as: (post-nephrectomy inulin clearance)/(0.5 x pre-nephrectomy inulin clearance); hyperperfusion was defined in an analogous way for PAH clearance. Hyperfiltration averaged 128 +/- 5% [SEM] and hyperperfusion 133 +/- 6% 1 week after uninephrectomy. Hyperfiltration was nearly unchanged (126 +/- 7%) 1 year after nephrectomy, whereas hyperperfusion had significantly decreased to 118 +/- 8% (P < 0.02). There was no significant change in blood pressure after nephrectomy, and no new cases of hypertension were observed during the 1-year follow-up. The degree of hyperfiltration did not correlate with donor age. Microalbuminuria > 30 mg/24 h was found in two donors 1 week after nephrectomy (one of which normalized at 1 year) and in one additional donor 1 year after nephrectomy. The degree of hyperfiltration did not correlate with albumin excretion rate. In conclusion, no adverse consequences of hyperfiltration were demonstrable during the 1-year observation period, but the prognostic role of occasional microalbuminuria should be further investigated.