Like "As little as I HAVE TO. Right now getting iron shots and liquid Zemplar (parathyroid med) with my dialysis treatments. I take a Rx vitamin called "vital D" which is for kidney patients. One of the things I learned is that many vitamins are cleared through the kidneys and when they are not working properly the excess vitamins are not cleared well. Somehow the excess vitamins in Vital D are cleared through the liver, so not so much work for the kidneys. "