Osteomalacia

Definition

Osteomalacia is softening of the bones due to a lack of vitamin D or a problem with the body's ability to break down and use this vitamin.

Causes, incidence, and risk factors

The softer bones seen in persons with osteomalacia have a normal amount of collagen, which gives the bones its structure, but lack the proper amount of calcium.

There are numerous causes of osteomalacia. In children, the condition is called rickets and is usually caused by low levels of vitamin D.

Other conditions that may lead to osteomalacia include:

• Not enough vitamin D in the diet
• Not enough exposure to sunlight, which produces vitamin D in the body
• Malabsorption of vitamin D by the intestines

Use of very strong sunscreen, limited exposure of the body to sunlight, short days of sunlight, and smog are factors that reduce formation of vitamin D in the body. The elderly and those who avoid drinking milk are at increased risk for osteomalacia.

Other conditions that may cause osteomalacia include:

• Cancer
• Hereditary or acquired disorders of vitamin D metabolism
• Kidney failure and acidosis
• Liver disease
• Phosphate depletion associated with not enough phosphates in the diet
• Side effects of medications used to treat seizures

Symptoms

• Bone fractures that happen with very little injury
• Muscle weakness
• Widespread bone pain, especially in the hips

Symptoms may also occur due to low calcium levels. These include:

• Abnormal heart rhythms
• Numbness around the mouth
• Numbness of arms and legs
• Spasms of hands or feet

Signs and tests

Blood tests will be done to check vitamin D, creatinine, calcium, and phosphate levels.

A bone biopsy reveals bone softening.

Bone x-rays and a bone density test can help detect pseudofractures, bone loss, and bone softening.

Other tests may be done to determine if there is a kidney problem or other underlying disorder. These tests include:

• ALP (alkaline phosphatase) isoenzyme
• PTH

Treatment

Treatment may involve vitamin D, calcium, and phosphorus supplements, taken by mouth. Larger doses of vitamin D and calcium may be needed for people who cannot properly absorb nutrients into the intestines.

Regular blood tests may be needed to monitor blood levels of phosphorus and calcium in persons with certain underlying conditions.

Expectations (prognosis)

Improvement can be seen within a few weeks in some people with vitamin deficiency disorders. Complete healing with treatment takes place in 6 months.

Complications

Return of symptoms is a possible complication.

Calling your health care provider

Call for an appointment with your health care provider if you have symptoms of osteomalacia, or if you think that you may be at risk for this disorder.

Prevention

A diet rich in vitamin D and getting plenty of sunlight can help prevent osteomalacia due to a vitamin D deficiency.

References

Wysolmerski JJ. Insogna KL. The Parathyroid Glands, Hypercalcemia, and Hypocalcemia. In: Kronenberg HM, Schlomo M, Polansky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. St. Louis, Mo: WB Saunders; 2008: chap. 266.

Bringhurst FR, Demay MB, Kronenberg HM. Disorders of Mineral Metabolism. In: Kronenberg HM, Schlomo M, Polansky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. St. Louis, Mo: WB Saunders; 2008: chap. 27.