Summary

The kidney plays a central role in vitamin D physiology. Chronic kidney disease (CKD) is associated with vitaminD deficiency, which becomes more severe with progressive loss of renal function. Children with CKD may develop potentially dramatic symptoms of vitaminD deficiency due to high physiological requirements of calcium and phosphorus for the growing skeleton. Failure of vitaminD substitution can lead to overt renal rickets especially in small children. Vitamin D deficiency in CKD is part of a complex disturbance including mineral metabolism (calcium, phosphorus, parathormone [PTH]), bone (mineralisation, growth) and arteries (vascular calcification). Patients with CKD and vitamin D deficiency therefore should be treated with cholecalciferol (D3) or ergocalciferol (D2) supplements. In addition, therapy with vitamin D receptor activators (e.g. calcitriol, alfacalcidol, paricalcitol) is indicated when renal synthesis becomes insufficient at higher stages of CKD. However, therapy with active vitamin D preparations should be closely monitored due to a narrow therapeutic window.