Hello, why you have doubt about your kidneys? If you are healthy and do not have symptoms like, swelling of legs, breathing difficulty, swelling of face, severe generalized weakness then you need not worry. If you still have doubt about your kidneys then go ahead with renal function tests. Urine routine will tell you about any infection in urinary tract and serum(blood) urea creatine will tell you about whether kidney is working normally or not. Both tests are 20min procedure.