Vitamin d-resistant rickets

Vitamin D-resistant rickets, now usually called X-linked hypophosphatemia, is an inherited kidney and bone disorder in which the body wastes phosphate, leaving blood phosphate low and the skeleton soft. It is caused by variants in the PHEX gene, located on the X chromosome, which raise a hormone-like protein, fibroblast growth factor 23, and so impair phosphate absorption and kidney reabsorption. The pattern is X-linked dominant, so females with one altered copy usually have features similar to males. It is typically diagnosed in childhood and causes slow growth, short stature, bowed legs, bone pain and severe dental pain, sometimes with dental abscesses; severity varies widely, even within one family. Adults may develop osteomalacia, stress fractures, painful joint attachments and osteoarthritis, and some people have premature fusion of the skull bones or hearing loss.

Seek urgent care for a fracture after a minor fall, a hot swollen joint with fever, or sudden severe back pain. See a doctor for joint pain and stiffness lasting more than six weeks, loss of height, or if you have risk factors for weak bones and have never had a bone-density assessment. Call the local emergency number for any symptom that is sudden and severe. This page is a reference for healthcare professionals and does not replace an assessment.