Donating a kidney when alive has no adverse effects on the donor or recipient after 5 years, even if the donor is older, overweight or has high blood pressure. This conclusion was drawn by researcher Hilde Tent of the University Medical Center Groningen, who will be awarded a PhD for her research by the University of Groningen on 11 July. The criteria for living kidney donation have been relaxed so that older people, even overweight people or people with high blood pressure, can qualify for donation, provided the donor kidney function is sufficient before donation.
Living kidney donation is becoming increasingly important in kidney transplantation. A kidney can be donated safely as a healthy kidney has a lot of reserve capacity. Now that the criteria allow older people, overweight people or people with high blood pressure to donate a kidney, identifying the long-term effects for both donor and recipient is very important.
Tent researched data on 160 donors and 196 recipients. Donors older than 55 years had, as expected, lower kidney function than younger donors both before and after donation. However, kidney function recovery over the long term was the same for both older and younger donors. For the recipient, the older age of the donor had no negative effect on the adaptive capacity of the kidney. Five years after a kidney transplant from an older donor, a good but slightly lower kidney function was measured in the recipients, when compared with the recipients of kidneys from younger donors. According to Tent, these effects could be attributed to normal ageing processes.
Since 2002, living kidney donation is possible for people with elevated blood pressure who are well-adapted to medication. Measurements revealed no differences in kidney function between donors with and without blood pressure-reducing medication two months and a year after donation. Moreover, blood pressure did not rise any further in donors who had elevated blood pressure after donation, in comparison with donors with normal blood pressure. They did not need any extra medication. A slightly lower kidney function was measured in recipients of the kidneys from donors with elevated blood pressure than in recipients of kidneys from entirely healthy donors. The theory that a kidney from a donor with high blood pressure would ‘transmit’ this disorder to the recipient was not confirmed in this research. The selection of donors with good kidney function probably played a role in this.
Immediately after donation, kidney function in a percentage of the donors was reduced to the point where they officially had a kidney disorder according to the established criteria for people with two kidneys. In her research on kidney transplantation, Tent sheds a different light on these criteria. Kidney function slowly declines with a ‘true’ kidney disease and increasing age. In cases where a kidney is donated, kidney function first declines sharply, but then quickly increases, after which it improves further over the years. Tent explained that this was due to the remaining kidney becoming bigger, developing more capacity, and kidney function returning to healthy values. Tent advocates annual kidney function checks for all donors to quickly spot any deterioration.
Tent determined that a kidney donated by a donor who was overweight had no negative effect on the donor after 5 years, or on the kidney function of the recipient. She also found no differences between the sexes. Tent showed that kidneys from female donors performed just as well as kidneys from male donors with the same body mass.
Over a period of 5 years, living kidney donation from older people, overweight people or people with high blood pressure has been shown to be safe for the donor and it provides good kidney function for the recipient. In her research, Tent used a very accurate kidney function test. ‘Consequently, we could measure the effects very accurately. Our research has provided the UMCG with a good basis with which to standardize the criteria for living kidney donation across Dutch transplantation centres’, said Tent. She recommended continuing the evaluation of donors and recipients to be able to determine the effects over an even longer period.
Hilde Tent (Groningen, 1985) studied medicine at the University of Groningen. She conducted her PhD research at the Department of Nephrology of the Internal Medicine section of the UMCG within the framework of the Junior Scientific Masterclass. The title of her thesis is ‘Living kidney donation: implications for donor screening and follow-up’.
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