Causes

Your child's body needs vitamin D to absorb calcium and phosphorus from food. Rickets can occur if your child's body doesn't get enough vitamin D or if his or her body has problems using vitamin D properly. Occasionally, not getting enough calcium or lack of calcium and vitamin D can cause rickets.

Lack of vitamin D

Children who don't get enough vitamin D from these two sources can develop a deficiency:

• Sunlight. Your child's skin produces vitamin D when it's exposed to sunlight. But children in developed countries tend to spend less time outdoors. They're also more likely to use sunscreen, which blocks the sun's rays that trigger the skin's production of vitamin D.
• Food. Fish oil, egg yolks and fatty fish such as salmon and mackerel contain vitamin D. Vitamin D has also been added to some foods and beverages, such as milk, cereal and some fruit juices.

Problems with absorption

Some children are born with or develop medical conditions that affect the way their bodies absorb vitamin D. Some examples include:

• Celiac disease
• Inflammatory bowel disease
• Cystic fibrosis
• Kidney problems