Not all rickets is vitamin D deficiency.

Although vitamin D deficiency is a common cause of rickets, other types of rickets, including hereditary forms, must be considered in the differential diagnosis. The patient described here presented for evaluation of bowing of his lower extremities, and was ultimately diagnosed with X-linked hypophosphatemic rickets, a disorder caused by renal wasting of phosphate that occurs as a result of a mutation in the PHEX gene.