Osteomalacia and Rickets
What is it?
Osteomalacia is a disorder marked by inadequate or defective mineralization of the skeleton, resulting in soft or fragile bones. It typically occurs either when there are insufficient amounts of vitamin D in the diet or, more commonly, when the body is unable to properly absorb and metabolize vitamin D, which is essential for the absorption of the calcium needed to maintain strong, healthy bones. It can also occur with calcium and phosphorus deficiency.When the disease occurs in children, it is known as rickets and tends to produce obvious skeletal deformities. The disease has more subtle manifestations in adults and may be difficult to diagnose or to differentiate from osteoporosis. In some cases repeated pressure on soft bones can lead to fractures or mild deformities. In adults, when osteomalacia is due to a vitamin D deficiency, treatment usually cures the problem within six months. In children, the disease may be arrested, although skeletal deformities may be permanent. Although common in underdeveloped countries, rickets is now rare in Western nations.
What Causes It?
- A chief cause of osteomalacia is intestinal malabsorption of vitamin D (see Malabsorption).
- Osteomalacia may be caused by disorders of any of the organs involved in vitamin D synthesis, such as the skin, kidney, and liver.
- Dietary deficiency of vitamin D is common, especially in the elderly and exclusively breast-fed infants. Vitamin D is supplied in the diet mainly through vitamin D-fortified dairy products and cereals. However, many adults do not consume enough.
- Inadequate exposure to sunlight reduces the amount of vitamin D produced naturally by the skin.
- Chronic renal failure and complications of hemodialysis are potential causes.
- Chronic acidosis (an abnormal state of reduced alkalinity in the blood or body tissues, usually due to renal failure) may lead to osteomalacia.
- Osteomalacia may occur as a side effect of some anticonvulsant drugs used to treat epilepsy. They interfere with normal activation of vitamin D.
- Several rare hereditary disorders can cause low phosphorus blood levels (hypophosphatemia), resulting in osteomalacia. Hypophosphatemia may also result from chronic use of nonabsorbable antacids.
Prevention
- Dietary intake of vitamin D-fortified foods (such as milk products) and adequate exposure to sunlight help prevent vitamin D deficiency.
Diagnosis
- Patient history and physical examination.
- X-rays to evaluate bone mass and fractures.
- Blood tests to measure vitamin D, calcium, phosphorus, parathyroid hormone levels, and alkaline phosphatase.
- Bone biopsy in some cases.
How to Treat It
- Oral supplements of vitamin D are given, sometimes in conjunction with calcium.
- For osteomalacia due to intestinal malabsorption, oral vitamin D or vitamin D injections may be needed. Calcium supplements may also be beneficial.
- Osteomalacia due to chronic renal failure requires correction of the acidosis.
- Disorders leading to low blood phosphorus are treated with large doses of oral phosphate supplements plus vitamin D metabolites.
- Skeletal deformities may be corrected surgically.
When to Call a Doctor
- Consult a doctor if you or your child experiences bone pain, unexplained fractures, or apparent limb deformities.
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Content excerpted from Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference.