A Prospective Controlled Study of Kidney Donors: Baseline and 6-Month Follow-up

Background: Most previous studies of living kidney donors have been retrospective and have lacked suitable healthy controls. Needed are prospective controlled studies to better understand the effects of a mild reduction in kidney function from kidney donation in otherwise healthy individuals. Study Design: Prospective, controlled, observational cohort study. Setting & Participants: Consecutive patients approved for donation at 8 transplant centers in the United States were asked to participate. For every donor enrolled, an equally healthy control with 2 kidneys who theoretically would have been suitable to donate a kidney also was enrolled. Predictor: Kidney donation. Measurements: At baseline predonation and at 6 months after donation, medical history, vital signs, measured (iohexol) glomerular filtration rate, and other measurements were collected. There were 201 donors and 198 controls who completed both baseline and 6-month visits and form the basis of this report. Results: Compared with controls, donors had 28% lower glomerular filtration rates at 6 months (94.6 +/- 15.1 [SD] vs 67.6 +/- 10.1 mL/min/1.73 m(2); P < 0.001), associated with 23% greater parathyroid hormone (42.8 +/- 15.6 vs 52.7 +/- 20.9 pg/mL; P < 0.001), 5.4% lower serum phosphate (3.5 +/- 0.5 vs 3.3 +/- 0.5 mg/dL; P < 0.001), 3.7% lower hemoglobin (13.6 +/- 1.4 vs 13.1 +/- 1.2 g/dL; P < 0.001), 8.2% greater uric acid (4.9 +/- 1.2 vs 5.3 +/- 1.1 mg/dL; P < 0.001), 24% greater homocysteine (1.2 +/- 0.3 vs 1.5 +/- 0.4 mg/L; P < 0.001), and 1.5% lower high-density lipoprotein cholesterol (54.9 +/- 16.4 vs 54.1 +/- 13.9 mg/dL; P = 0.03) levels. There were no differences in albumin-creatinine ratios (5.0 [IQR, 4.0-6.6] vs 5.0 [IQR, 3.3-5.4] mg/g; P = 0.5), office blood pressures, or glucose homeostasis. Limitations: Short duration of follow-up and possible bias resulting from an inability to screen controls with kidney and vascular imaging performed in donors. Conclusions: Kidney donors have some, but not all, abnormalities typically associated with mild chronic kidney disease 6 months after donation. Additional follow-up is warranted. (C) 2013 by the National Kidney Foundation, Inc.