Living donor kidney transplantation (LDKT) has increased significantly in the past 10 years. Currently it accounts for 41% of all kidney transplants in the USA.1 While the percentage is lower in the United Kingdom and other European countries, the number of living compared with cadaveric kidney donors will probably continue to increase globally. Mortality associated with surgery on live donors is low, thanks largely to the success of laparoscopic nephrectomy. Kidney transplantation from a living donor is preferable to that from a cadaveric, or deceased, donor because of its superior graft and patient survival outcomes. It also preempts the need for or reduces the duration of dialysis for individuals with end-stage renal disease (ESRD) and therefore greatly improves their quality of life.

Some who donate kidneys to anonymous recipients are motivated by altruism, with no direct benefit and only an indirect psychological benefit as a consequence of donating. Those who donate may be motivated by prudential reasons involving shared interests, or by a sense of obligation grounded in emotional relations. This includes donations between spouses, siblings, parents and children and may also include donations between intimate friends. Others may be motivated to donate by the prospect of financial gain. In a recent article on kidney markets, The Economist claimed that those who donate one of their healthy kidneys do so at “very little risk to their health”.2 Presumably, this provides support for these markets. In 2004, Zell Kravinsky, an American in his early 40s, gave away one of his healthy kidneys to a stranger as part of a utilitarian obligation to help other people and maximise the good by saving or improving the quality of their lives.3 He estimated that this entailed a statistically insignificant risk to his health. In a lecture to an ethics class at Princeton University conducted by utilitarian philosopher Peter Singer, Kravinsky claimed that his chances of dying as a result of donating a kidney were about 1 in 4 000.4 Yet recent data suggest that the long-term risk in living kidney donation and the personal cost may be higher than previously thought. This risk may become more significant given the increasing incidence of hypertension and especially diabetes in both developed and developing countries, where it is the most common cause of end-stage renal disease.5

This raises ethical questions about what constitutes permissible risk in transplantation, whether the benefits of living kidney donation clearly outweigh any costs to the donor, and the extent to which transplant surgeons and the medical community should promote LDKT.6 More generally, LDKT raises the question of how to weigh the physician’s duty to do no harm to the patient against patients’ autonomous choice to put themselves at some risk of harm in order to benefit others. These questions have been raised mainly with respect to the surgical transplant procedure itself but seldom with respect to the period beyond the surgical procedure of procuring the organ for transplantation. The risks associated with living donor liver lobe transplantation are greater than those associated with living donor kidney transplantation.7 Nevertheless, the risks in LDKT deserve more attention.

One 2005 report stated that 56 of 50 000 previous kidney donors in the USA had ultimately been listed for transplants themselves.8 A more recent report gives a higher number, stating that 104 Americans on the current transplant list had previously been live donors.9 Conditions such as X-linked hereditary nephritis are now known to be contraindications to donation and are listed among exclusionary criteria. But the increasing incidence of diabetes may be the most significant factor influencing risk. Physician Julie Ingelfinger provides an account of a teenage boy with ESRD who received a kidney from his mother, then in her early 40s.10 The recipient died a few years after the transplant. The mother, considered to be in perfect health with no known risk factors for renal disease, subsequently developed insulin-dependent diabetes. Her remaining kidney failed and she would have required dialysis and a place on the transplant waiting list but died of a myocardial infarction. The association between living kidney donation and renal disease is unclear and warrants a critical re-evaluation of living kidney donation, with a more careful assessment of the probable long-term outcomes for healthy donors.

Most recipients of kidneys transplanted from living donors benefit in terms of better graft survival and independence from dialysis. Many living donors benefit emotionally, though it is unclear whether this benefit might diminish over time in cases where the transplant fails. Even when there is a sustained emotional benefit, this has to be weighed against the long-term physiological risk to the donor. The factors justifying reassessment of the risk–benefit ratio in LDKT are the following. First, graft survival of organs from living donors in transplant recipients is not permanent, as recipients may need a second transplant after 20 or 30 years. There is also a constant risk of earlier organ rejection and failure due to ischaemia and MHC processes in the period between organ procurement and transplant. Admittedly, this factor has to be considered relative to the risk of dying on dialysis, as well as the age of the recipient. Second, immunosuppression to sustain the graft puts the recipient at risk of potentially life-threatening infections. Third, and most importantly, healthy living donors unscathed by transplant surgery might subsequently develop diabetes and ESRD. If this occurred, then the loss in quality life years for a person who was healthy at the time of donation and surgery could be considerable.

Emotional benefit post transplant can go only so far if the donor develops a disease incurring a risk of kidney failure. Most donors who develop complications as a consequence of this action insist that they would donate again and that any risk was more than worth it. Yet even if patients were willing to do this, should physicians as moral agents be permitted to expose potential donors to this risk? At what point does the risk become medically and morally significant? Individuals in ESRD for whom dialysis is not optimal therapy have a need for a kidney transplant. But physicians have a greater duty of care to healthy individuals willing to donate a kidney, because they have more to lose from donating than individuals in ESRD who do not receive a transplant from a living donor. It is worse for a healthy individual to become sick as a consequence of a procedure that is not medically necessary than for an individual in kidney failure not to receive a transplant from a living donor. The latter can survive for a period of time on dialysis, which is a form of renal replacement therapy. Alternatively, the patient may receive a kidney from a cadaveric donor. The recipient’s quality of life may be better for a longer period with an organ from a living donor. Yet the difference between the quality and quantity of life for the recipient with a kidney from a cadaveric or a living donor is not as significant as the difference between health and disease for an individual who subsequently develops renal complications associated with the donation. In the light of this, we need to ask whether a living donor might be sacrificing too much in giving up a kidney to benefit another.11

Zell Kravinsky’s kidney donation was part of a larger utilitarian obligation that included giving away a substantial amount of money he had earned in real estate. Leaving aside the question of whether his moral obligation to maximise the good outweighed his moral obligation to his family, it is possible that he might not be able to fulfil the first obligation. If he developed diabetes or hypertension and his remaining kidney ceased to function, then he would end up on dialysis and the transplant waiting list. This might preclude him from maintaining the income that would have enabled him to continue giving away his wealth. It could also add to the costs of the healthcare system, since long-term dialysis is more costly than a kidney transplant. While donating his kidney clearly benefited the woman who received it, by improving the quality of her life and possibly saving it, in the long term it could result in net disutility rather than net utility if it led to kidney disease and prevented him from realising his utilitarian goal.

More careful selection criteria for contraindications to living donation will reduce the incidence of adverse outcomes for donors. Non-maleficence is not an absolute moral duty in medicine, however. Physicians and transplant surgeons are allowed to expose organ donors to some degree of risk when organ donation and transplantation have a net benefit. A physician’s duties to a patient should not be paternalistic and accordingly should include respect for a competent patient’s autonomous decision to undergo a procedure that may entail some degree of risk. Yet it is not known at what degree of risk the physician’s duty to do no harm would outweigh the patient’s autonomy. It is not known how many living kidney donors will subsequently develop conditions such as diabetes and hypertension and unwittingly put themselves at risk of developing ESRD by donating a kidney. In these cases, glucose intolerance and hypertension would not be evident at the time of donation. The number of healthy donors who have developed diabetes and/or hypertension after donation to date may not be statistically significant enough for one to argue that the risk is impermissible. There presently are no compelling grounds for arguing that living kidney donation should be prohibited or become much more restricted. Data on long-term health outcomes for healthy living donors are necessary to clarify the risk. This would have to include clarification of whether donation is a direct or indirect causal factor in ESRD, or whether the association between donation and ESRD is only apparent and not real.

Although the short-term benefit–risk ratio in LDKT is favourable for recipients and donors, the long-term benefit–risk ratio for donors might not be so favourable, especially in the light of the increasing incidence of diabetes. These considerations suggest that medical professionals should do more to promote cadaveric organ donation—where there is no risk to the donor—to meet transplant needs. Graft survival for the recipient may not be as good as in living donation. But at least it meets a need without putting healthy individuals at risk of harm.