Prospective Measurement of Urinary Microalbumin in Living Kidney Donor Nephrectomy: Toward Understanding the Renal Functional Recovery Period

Abstract

Purpose: We determined the clinical implications of perioperative urinary microalbumin excretion in relation to renal function after living donor nephrectomy.

Materials and Methods: Between August 2010 and January 2013, 259 donors undergoing live donor nephrectomy were enrolled in the study. The donor urinary albumin-to-creatinine ratio was measured perioperatively, and changes in perioperative urinary albumin-to-creatinine ratio and the implications of preoperative microalbuminuria (urinary albumin-to-creatinine ratio 30 mg/gm or greater) were investigated. The relationships between perioperative urinary albumin-to-creatinine ratio and recovery of renal function and implantation biopsy histology were also analyzed.

Results: Mean +/- SD preoperative urinary albumin-to-creatinine ratio was 7.1 +/- 12.7 mg/gm. The urinary albumin-to-creatinine ratio was increased after 1 day (24.7 +/- 18.9 mg/gm, p < 0.001) and stabilized after 1 month (10.3 +/- 10.7 mg/gm, p < 0.001). Preoperative microalbuminuria was not associated with perioperative estimated glomerular filtration rate during a followup period of 6 months but was associated with histological abnormalities. Donors with a higher urinary albumin-to-creatinine ratio before donation, even in the normal range, consistently had an increased postoperative urinary albumin-to-creatinine ratio. A ROC curve analysis showed that age, preoperative estimated glomerular filtration rate and 1-month postoperative urinary albumin-to-creatinine ratio were highly predictive of delayed recovery of renal function (AUC 0.884, p < 0.001). The 1-month postoperative urinary albumin-to-creatinine ratio was associated with delayed recovery of renal function (OR 1.05 for each 0.1 mg/gm increase, p = 0.021).

Conclusions: Donors with higher preoperative urinary albumin-to-creatinine ratio levels require close observation because there is a greater possibility of microalbuminuria developing after donation even if the ratio is within the normal range. A higher urinary albumin-to-creatinine ratio was also associated with delayed recovery of renal function and histological abnormalities.