Prospective measurement of urinary microalbumin in living kidney donor nephrectomy: Toward understanding the renal functional recovery period

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.