Abstract: Vitamin D is an important nutrient involved in bone mineral metabolism. In most cases, serum total 25-hydroxyvitamin D (25[OH]D) level represents vitamin D content in the body. Genetic polymorphism in vitamin D binding protein affects the bioavailability of 25(OH)D. There is no consensus about the definition of vitamin D insufficiency and deficiency. Vitamin D insufficiency or deficiency is highly prevalent in patients with chronic kidney disease (CKD) and is closely related to the development and progression of CKD. Vitamin D insufficiency or deficiency is also the risk factor for the progression of renal insufficiency finally to end-stage renal disease necessary to be treated with renal replacement therapy, and also for the renal anemia, cardiovascular events and death in CKD patients. Supplement of vitamin D can increase serum total 25- hydroxyvitamin D concentration, decrease the elevated parathyroid hormone concentration, and improve proteinuria, risk of falls, cardiac and vascular function and prognosis in CKD patients.

Key words: vitamin D, chronic kidney disease, prognosis