I relied on the one fact that would be repeated to me many times: “The rate of kidney failure in kidney donors is the same as the general population.” Why wouldn’t everyone donate a kidney, I wondered…

Five years after the surgery, when I was 23 and getting ready to go to medical school, I began working in a research lab that was looking at kidney donors who had gone on to develop kidney failure. For that research, I talked to more than 100 such donors. In some cases, the remaining kidneys failed; in others, the organ became injured or developed cancer. The more I learned, the more nervous I became about the logic of my decision at age 18 to donate.

And then in 2014, a study looking at long-term risks for kidney donors found that they had a greater risk of developing end-stage renal disease. Another study that same year raised the possibility that they may face a heightened risk of dying of cardiovascular disease and all-cause mortality (although this point remains controversial).