AnnieK
One of our best friends who was a school superintendent had one kidney (not knowing it) and was very athletic in younger yrs (played football) and played tennis in adult yrs. Was in good health as far as I know until he developed cancer in late 50's. Raised family etc. Also best friend of my sisterin-law is in her 70's and has been living with one kidney for abt 30 yrs. I do remember our supt. friend saying if he had known when he was younger, they would not have let him play contact sports so I assume there is a risk of getting hit in that area and damaging the one kidney. Raised 5 children and we are athletic family so understand how very important this is to your son at this time in his life. Am sure you will get many posts,God bless and give you much wisdom....