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.

Keywords: albuminuria; delayed graft function; kidney transplantation; living donors; nephrectomy.