What made you say that only 51% of your kidneys are working? The best way to determine differential kidney function is through a Glomerular Filtration Rate (GFR) done in a Nuclear Medicine Facility. Serum Creatinine
is Okay. Crea Clea is more than okay. CBC is also okay.
Ctscan - A extrarenal pelvis means it is a normal variant and has no clinical significance. Also the dromedary hump is also a normal variant which has no clinical significance.
All in all I think you are in fine shape Mr. Bob and have a nice day.