When I was a bit fitter than I am now, but still on haemodialysis I climbed Puy-de-Dome mountain (1464m) in Central France.
It was raining at the bottom (September) and took 2 hours to traverse the path, where it was snowing at the top!
I found my breathing was a little laboured over 1000m but I was really exhilarated by the climb.
I ate a decent cooked breakfast beforehand, but besides water took a flask of sweetened hot chocolate which really
helped. Something sweet will help be it a Mars bar or something and the small amount of chocolate shouldn't hurt your renal diet.
Take fluids. And pace yourself. Good luck.
Let us know on here how you do