If you obtain a full written medical/renal clearance from the medical nephrologist than I see no reason not to have a full TT. Seek 3 boarded surgeons opinions in your area. From MIAMI Dr. Darryl J. Blinski, 305 598 0091
Chronological age is a relative indicator. Your physiological age is more important. If you are healthy and the benefits to you is significant, a tummy tuck may be possible at your age or even older. There are also variation to a tummy tuck that may make the procedure less risky or painful. You need to consult with your family doctor and a board-certified plastic surgery.