From NCL.com:
Dialysis
Guests requiring continuous ambulatory peritoneal dialysis are welcome to board all vessels. However, Norwegian Cruise Line does not have the ability to assist or administer hemo-dialysis treatments. Those guests using peritoneal dialysis should have all solutions and equipment needed to perform the dialysis delivered to the vessel on the day of sailing at least two hours prior to sailing. Please contact the Access desk prior to the cruise for more information on Norwegian Cruise Line's policies and procedures.