Hello. I read your question carefully and I must say I am impressed by your generosity toward your uncle. Regarding your question, if both your kidneys are working well (of course their function will be carefully evaluated prior to the donation by your transplant doctors) you can get on fine with the one kidney, those drugs are mainly metabolized by the liver anyway, only serious kidney impairment would make their use contraindicated. As I said you should be carefully evaluated before though. You don t say what type of brain tumor you ve had surgery for. Even though it s been already 6 years, if there is even a slight chance it may reoccur and chemotherapy is involved, you might think twice as your kidneys would be on extraload due to chemio, that s why even a distant history of cancer is a relative contraindication for kidney donation. Hope things work out for best for you and your uncle. Feel free to ask further questions.