Kidney Donation
IC, I would have to say do it if you can. The recovery period for the donor is at times longer than that of the one who receives the Kidney. I have first hand knowledge of this, since last October, my wife donated one of her Kidneys to me. In May of this year, the FAA reissued my 1st Class Medical. I had to jump through a lot of hoops, and will continue to have to do so for the remainder of my career.
So in my personal opinion, you should not have a problem getting certified medically.