Immediately after donation, living donors show mild signs of kidney disease, but actually improve their kidney function over time, according to the results of a prospective study published in the July issue of the American Journal of Kidney Diseases.

The three-year, follow-up study of living kidney donors and paired controls, funded by the National Institutes of Health, is the only prospective study on the health of living kidney donors currently in progress in the United States. “We’ve always assumed that living kidney donation is safe, and it is, but safety is a relative thing,” said lead researcher Bertram Kasiske, MD, of Hennepin County Medical Center in Minneapolis, Minn. “There have not been the long-term studies with suitable controls that we need to prove the safety of living kidney donation over time.”

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The study, now in its sixth year of assessing donors and controls, is looking specifically at medical history, vital signs, kidney function, and lab values of donors.

The most interesting finding so far, said Kasiske, is that kidney function, measured by glomerular filtration rate, changes between 6 and 36 months after donation. It declined -0.44  mL/min/1.73m2 per year in 194 controls, but increased 1.09 mL/min/1.73m2 per year in 198 living donors. Blood pressure was also stable and within normal ranges for donors. “It looks like the remaining kidney is still compensating for the loss in function at three years after donation,” said Kasiske. “It will be interesting to see if these kidney function increases continue over time.”

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