What is Vitamin D Resistant Rickets?

T. Carrier

Rickets is a childhood condition that makes bones weak and brittle. Although a large percentage of cases result from malnourishment, some cases are caused by a genetic mutation. One such genetic variation leads to low levels of the substance phosphate in the body. This type is known as vitamin D resistant rickets, or X-linked hypophosphatemia.

Malnourishment is the leading cause of rickets, putting children in third world countries at an increased risk.
Malnourishment is the leading cause of rickets, putting children in third world countries at an increased risk.

Bone-related issues are the primary indicator of Vitamin D resistant rickets. The softness of the bones often causes them to curve and become deformed. Curves in the legs, chest, and back are particularly common. In addition, the condition can alter the shape of the skull and thus give it a squarish appearance. Vitamin D resistant rickets also makes afflicted individuals more vulnerable to bone fractures and bone pain.

Additional symptoms also correlate with Vitamin D resistant rickets. These include tooth-related issues, chest swelling, and enlargement of the wrist. Muscles are often adversely affected as well, as they may become abnormally weak or suffer uncontrollable spasms.

Vitamin D resistant rickets sets off a chain reaction in the body, beginning with the kidneys. One or more kidney tubes malfunction due to the presence of the rickets abnormality, which causes a substance known as phosphate to concentrate in urine instead of blood. As a result, the blood does not have enough phosphate to supply bones. Since phosphate helps bones remain strong, the absence of it causes bone deformity.

This condition is made worse by a lack of vitamin D. Vitamin D is a vital component of proper calcium distribution in the body. Calcium, in turn, is one of the primary building components of bones: diminished calcium results in diminished bone strength.

Rickets may be caused by malnourishment or by an inherited gene defect. Vitamin D resistant rickets is a genetic condition. It is typically found as a mutation in an individual’s X chromosome, and is passed along as a dominant trait.

Traditional treatment of rickets depends on two approaches: proper nutrition and sunlight exposure. Foods like fish and dairy products contain Vitamin D, so ingestion of these substances or certain oils may be recommended. Vitamin D can also be found in ultraviolet (UV) light, so certain levels of UV exposure offer another treatment option. Vitamin D resistant rickets is often immune to the effects of Vitamin D alone, however. Therefore, treatment of this condition usually requires intake of phosphate as well as a medical form of Vitamin D.

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