A person with rickets has abnormal bone development that results in softening and weakening of the bones. Rickets is caused by a lack of vitamin D, calcium, or phosphate. Decreased levels of these nutrients are usually caused by another underlying illness.

Rickets is rare in the United States. It is most common during periods of rapid growth, when the body requires calcium and phosphate for bone growth. Rickets is most common in young children, who are between 6 and 24 months of age.

A balanced diet is an adequate source of vitamin D. However, the body also manufactures vitamin D in the skin when it is exposed to sunlight.