I don't really know what it's like to live with 2 kidneys. I had a nephrectomy at the age of 4 (currently 39). I have lived a very normal healthy life. I do watch my labs closely, every 6 months checking levels. And in the last few years I've had a UPJ obstruction that has caused some havok. I am awaiting a surgery in January at Mayo to repair the ureter. I do notice I tire more easily than others, I just attributed that to my poor diet choices, but it could be the single kidney as well.