Living kidney donors exhibit some findings of mild chronic kidney disease (CKD) from 6 to 36 months post-donation, according to a recently published study. At 36 months, however, kidney function continues to improve in donors, whereas controls eligible for kidney donation experience expected age-related declines in function, researchers concluded.
“We’ve always assumed that living kidney donation is safe, and it is, but safety is a relative thing,” said lead investigator Bertram L. Kasiske, MD, of the Hennepin County Medical Center and University of Minnesota in Minneapolis. “There have not been the long-term studies with suitable controls that we need to prove the safety of living kidney donation over time.”
The study compared living kidney donors with a control group of individuals who met eligibility criteria for kidney donation at the donors’ transplant center, but did not undergo renal imaging or invasive testing. The investigators obtained medical histories, vital signs, measured glomerular filtration rate (mGFR), and other measurements at 6, 12, 24, and 36 months after donation.
The 2 groups differed significantly in the change in mGFR after donation. From 6 to 36 months, mean mGFR, as measured by plasma iohexol clearance, increased by 1.09 mL/min/1.73 m2 per year among 198 donors but declined by 0.44 mL/min/1.73 m2 per year among 194 controls, Dr. Kasiske’s group reported online ahead of print in the American Journal of Kidney Diseases. Blood pressure (BP) measurements did not differ between donors and controls at any visit; at 36 months, all 24-hour ambulatory BP parameters were similar in 126 controls and 135 donors. Urinary protein-creatinine and albumin-creatinine ratios were not increased in donors versus controls. Compared with controls, donors at 6 to 36 months had higher serum parathyroid hormone, uric acid, homocysteine, and potassium levels and lower hemoglobin levels. These abnormalities could portend a higher risk of fractures or bone problems later in life, Dr. Kasiske said, and elevated uric acid levels coincide with reports of increased rates of gout in some kidney donors.
At 36 months, 183 (89.7%) of the 203 original donors and 173 (86.1%) of the original controls continue to participate in follow-up visits.