to Purrs and sorry it is under sad circumstances but, as Gill says, a cat with kidney problems can go on for some time. Just don't panic
Our Fred has CRF but, although his last blood tests were not good, I am buoyed on by the fact that we are managing to maintain his weight at the moment. So here goes for what it's worth...
He is starving all the time and is continually wanting food and drinking. He has stopped moulting. Big chucks on fur have come out and the is very bald in places , he is very thin.
This doesn't sound like "just" kidney problems. Sounds more like Hyperthyroid "HyperT" problems. What tests did vet carry out? Was one of those tests for thyroid (T4)? Did you get a copy of blood test results? Is it possible that Henry has both conditions? If he has, then that makes his problem a little more complicated as, strangely, HyperT helps the kidney function better so any treatment for HyperT can affect kidney function.
I am concerned that you are just like me
and panicked at the vets and were not able to concentrate on what you were being told?
Somehow need to force yourself to stay clam when you speak to vet.
I now realise I have to cut out some protein
For kidney problems, it's the opposite. A cat with CRF is unable to retain as much protein as normal so it is imperative that he is fed
high quality protein and cooked chicken is excellent in that respect. I would give the tinned tuna a miss though. I am finding Royal Canin Renal wet food helpful for Fred at the moment (he eats both flavours but prefers the beef to the tuna) which is also low in phosphates which is also important. It is expensive but I firmly believe it is keeping him alive and maintaining his weight.
http://www.vetuk.co.uk/royal-canin-veterinary-diets-royal-canin-renal-c-62_65_77/royal-canin-renal-feline-so-12-x-100g-pouches-p-279Fred is also on benezacare tablets (1/2) a day which does the same job as the more generally known Fortekor but obviously your vet will know what is best for Henry.
Best of luck and hope you have along time with each other now that you know there is a problem and also ways to help him