@donnamaer Welcome to Mayo Clinic Connect. That is very adorable to want to donate a kidney to your son! Being able to donate as a living donor at your age would be at the decision of the transplant center where you son is listed at. There is quite a battery of tests to go through for the donor to be approved, and several factors to be considered.

As to your question, only one kidney is transplanted. Where is your son listed to be on the transplant list? Has he gone through the evaluation process to be a recipient, yet?
Ginger