Osteomalacia in children

Definition

Rickets is a disorder primarily caused by lack of vitamin D, calcium, or phosphate, which leads to softening and weakening of the bones.

Alternative Names

Causes

Vitamin D helps the body properly control calcium and phosphate levels in the body. When the body is deficient in vitamin D, it is unable to properly control calcium and phosphate levels. If the blood levels of these minerals become too low, the body may produce other body hormones to stimulate release of calcium and phosphate from the bones. This leads to weak and soft bones.

Vitamin D may be absorbed from food or may be produced by the skin when the skin is exposed to sunlight. Lack of vitamin D production by the skin may occur in people who must stay indoors, work indoors during the daylight hours, or live in climates with little exposure to sunlight.

Because vitamin D is a fat-soluble vitamin, malabsorption disorders that reduce digestion or absorption of fats will decrease the ability of vitamin D to be absorbed into the body.

You may not get enough Vitamin D from your diet if you follow a vegetarian diet, do not drink milk products, or are lactose intolerant (have trouble digesting milk products). Infants who are exclusively breastfed may develop vitamin D deficiency. Human breast mil does not supply the proper amount of vitamin D. This can be a particular problem for darker-skinned children in winter months (when there are lower levels of sunlight).

Not getting enough calcium and phosphorous in your diet can also lead to rickets. Rickets caused by a dietary lack of these minerals is rare in developed countries because calcium and phosphorous are found in milk and green vegetables.

Your genes may increase your risk of rickets. Hereditary rickets is form of the disease that is passed down through families. It occurs when the kidneys are unable to retain the mineral phosphate. Rickets may also be caused by kidney disorders that involve renal tubular acidosis.

Occasionally, rickets may also occur in children who have disorders of the liver, or cannot convert vitamin D to its active form.

Rickets is rare in the United States. It is most likely to occur during periods of rapid growth, when the body demands high levels of calcium and phosphate. Rickets may be seen in young children 6 to 24 months old and is uncommon in newborns.

Symptoms

• Bone pain or tenderness
  • Arms
  • Legs
  • Spine
  • Pelvis
• Skeletal deformities
  • Bowlegs
  • Forward projection of the breastbone (pigeon chest)
  • Bumps in the rib cage (rachitic rosary)
  • Asymmetrical or odd-shaped skull
  • Spine deformities (spine curves abnormally, including scoliosis or kyphosis)
  • Pelvic deformities
• Increased tendency toward bone fractures
• Dental deformities
  • Delayed formation of teeth
  • Defects in the structure of teeth, holes in the enamel
  • Increased incidence of cavities in the teeth (dental caries)
  • Progressive weakness
  • Decreased muscle tone (loss of muscle strength)
• Muscle cramps
• Impaired growth
• Short stature (adults less than 5 feet tall)

Exams and Tests

A physical exam reveals tenderness or pain in the bones, rather than in the joints or muscles.

The following tests may help diagnose rickets:

• Blood tests (serum calcium) may show low levels of calcium.
  • Tetany (prolonged muscle spasm) may occur if serum levels of calcium are low.
  • Chvostek's sign may be positive (a spasm of facial muscles occurs when the facial nerve is tapped) indicating low serum levels of calcium.
• Serum phosphorus may be low.
• Serum alkaline phosphatase may be high.
• Arterial blood gases may reveal metabolic acidosis.
• Bone x-rays may show loss of calcium from bones or changes in the shape or structure of the bones.
• A bone biopsy is rarely performed but will confirm rickets.

• PTH
• Urine calcium
• Calcium (ionized)
• ALP (alkaline phosphatase) isoenzyme

Treatment

The treatment goals are to relieve symptoms and correct the cause of the condition. The underlying cause must be treated to prevent recurrence.

The replacement of deficient calcium, phosphorus, or vitamin D will eliminate most symptoms of rickets. Dietary sources of vitamin D include fish, liver, and processed milk. Exposure to moderate amounts of sunlight is encouraged. Treating rickets caused by metabolic abnormalities may require a special prescription for vitamin D.

Positioning or bracing may be used to reduce or prevent deformities. Some skeletal deformities may require corrective surgery.

Outlook (Prognosis)

The disorder may be corrected with replacement of deficient minerals and vitamin D. Laboratory values and x-rays usually improve after about 1 week, although some cases may be resistant and require large doses of minerals and vitamin D.

If rickets is not corrected while children are still growing, skeletal deformities and short stature may be permanent. If it is corrected while the child is young, skeletal deformities often diminish or disappear with time.

Possible Complications

• Chronic skeletal pain
• Skeletal deformities
• Skeletal fractures, may occur without cause

When to Contact a Medical Professional

Call your child's health care provider if you notice symptoms of rickets.

Prevention

Rickets may be avoided by having your child maintain an adequate intake of calcium, phosphorus, and vitamin D. This may require dietary supplements in people who have gastrointestinal or other disorders -- ask your child's health care provider.

Renal (kidney) causes of vitamin D malabsorption should be treated promptly. Levels of calcium and phosphorus should be monitored regularly in people who have renal disorders

Genetic counseling may help people with a family history of inherited disorders that can cause rickets.