Q. Why can people survive with just one kidney?
A. The kidneys are fist-size organs that filter waste from about 200 quarts of blood per day, produce urine, regulate the balance of fluid and electrolytes in the body, release hormones that control blood pressure and red blood cell production, and manufacture vitamin D for the body. Perhaps because they’re so critical, our two kidneys together create a highly redundant system capable of doing much more than it needs to.
Joseph Bonventre, chief of the Renal Division at Brigham and Women’s Hospital, says that when healthy adults donate a kidney to a patient who needs a transplant, “there’s plenty of function left in the other kidney to meet demands.” Redundancy of function is one reason; another is that the remaining kidney actually grows somewhat to compensate.
Like all major surgeries, kidney donation carries risks, and ongoing research is examining whether donors face any long-term health consequences. So far, living with one kidney appears not to cause health problems for the vast majority of patients, provided they are properly screened beforehand. Bonventre points out that physicians, who take an oath to “do no harm,” are by and large supportive of living kidney donation, and “that reflects the fact that most of us think we’re not doing any harm to an individual in promoting this.”