Development and maintenance of a strong skeleton requires the addition of calcium and phosphorus to growing bone through a process called mineralization. Normal mineralization requires a child’s diet to include adequate supplies of both calcium and phosphorus.
What is rickets?
Rickets refers to the deficient mineralization and defective organization of cartilage at the growth plate and is only seen in children. Because the growth plates at the ends of the long bones are where lengthening of these bones occurs, children with rickets will experience poor height growth. Rickets can occur due to severe deficiency of calcium or phosphorus.
What are signs and symptoms of rickets?
- Progressive deformities of lower extremities
- Bowed or knocked knees
- Enlarged and softened skull
- Swollen bumps on the ribs
- Abnormal or waddling gait
- Tender and swollen wrists
- Bone pain
- Muscle weakness
- Generalized fatigue
- Poor growth
- Seizures due to low calcium levels
Causes of rickets
There are many different forms of rickets, both acquired and genetic. Nutritional rickets secondary to vitamin D deficiency is the most common form, especially in children from 6 months to 18 months of age. This is because the body is unable to absorb dietary calcium in the intestine without an adequate supply of vitamin D.
Genetic defects that impair activation of vitamin D to its hormonal form or which lead to rapid inactivation of vitamin D metabolites can also cause rickets. Rickets can also occur in children whose diet is severely deficient in calcium.
Rickets due to phosphorus deficiency can be a complication of prematurity, inadequate supply of phosphorus in the diet or impaired absorption of phosphorus in the intestine. Phosphorus deficiency can also occur as a result of excessive loss of phosphorus by the kidneys.
How is rickets diagnosed?
Rickets is diagnosed by physical examination and with X-rays. Laboratory tests that evaluate the concentrations of minerals (calcium and phosphorus in the blood and urine), vitamin D metabolites, PTH and alkaline phosphatase can help determine the cause of rickets. Genetic testing may be considered.
How is rickets treated?
The treatment of rickets depends on the specific mineral and/or vitamin deficiency. For nutritional rickets, children will be given high doses of vitamin D and supplemental calcium. Specific forms of vitamin D may be required to treat patients who have rickets caused by defects in vitamin D metabolism.
Rickets caused by phosphorus deficiency will be treated using phosphorus supplements, often with an active form of vitamin D (calcitriol). Some forms of hypophosphatemic rickets can now be treated with an injectable medication that improves retention of phosphorus by the kidneys and normalizes vitamin D metabolism.
Can rickets be prevented?
The key to preventing rickets is to ensure that all children meet their daily requirements for vitamin D intake, either through judicious sunlight exposure in the summer months or through ingestion of vitamin D-rich foods.
When children cannot meet their daily requirements for vitamin D through their diet and sunlight exposure, they may need to take a daily vitamin D supplement.
Outlook for children with rickets
The long-term outlook for rickets depends on the type of rickets and the age of diagnosis.