Abstract
Vitamin D exists in various forms and plays a central role in the absorption and regulation of calcium and phosphate. In chronic kidney disease, vitamin D concentrations become progressively reduced with the deterioration of kidney function, which becomes even more pronounced in end-stage kidney disease. Herein, we aim to summarize existing data regarding the pathogenetic role of vitamin D in dialysis and the potential effect of supplementation of various forms of vitamin D on hard and surrogate clinical endpoints. We performed a narrative review, gathering existing observational and clinical studies from 2001 to 2025 in English in the Medline/PubMed database, along with current guidelines and consensus statements regarding the use of vitamin D and D analogues in end-stage kidney disease patients. Vitamin D should be monitored and corrected, but supraphysiologic doses should be avoided, as well as very high levels of vitamin D to avoid toxicity. In dialysis, native D is used only to correct vitamin D deficiency; the real target here is secondary hyperparathyroidism, where vitamin D analogues and calcimimetics should be administered.