Vitamin D-resistant rickets is a group of rare disease characterized by lack of reaction to vitamin D administered in doses sufficient to manage patients with rickets caused by vitamin D deficiency. These disorders result from disturbed metabolism and activity of vitamin D and/or disturbed phosphate metabolism. The most common vitamin D-resistant form of rickets is X-linked hypophosphatemic vitamin D-resistant rickets. Other forms are as the following: oncogenic hypophosphatemic osteomalacia, autosomal dominant hypophosphatemic rickets, hereditary hypophosphatemic rickets with hypercalciuria and pseudo-vitamin D deficient rickets type I and II.