Osteomalacia Health Article

Definition

Osteomalacia is softening of the bones, caused by not having enough vitamin D, or by problems with the metabolism (breakdown and use) of this vitamin. These softer bones have a normal amount of collagen that gives the bones its structure, but they are lacking in calcium.

Causes, incidence, and risk factors

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

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

Other conditions that may cause osteomalacia include:

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

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.

Risk factors for osteomalacia are related to the causes. In the elderly, there is an increased risk among people who tend to remain indoors and those who avoid milk because of lactose intolerance.

Symptoms

• Diffuse (not pinpointed to one location) bone pain, especially in the hips
• Muscle weakness
• Bone fractures that happen with very little trauma

Symptoms associated with low calcium including:

• Numbness around the mouth
• Numbness of extremities
• Spasms of hands or feet
• Abnormal heart rhythms

Signs and tests

• Bone biopsy shows osteomalacia.
• Serum vitamin D level may be low.
• Serum calcium levels vary with the cause of the disorder.
• Serum phosphate levels vary with the cause of the disorder.
• Bone x-ray may show features of osteomalacia (such as bowing of the legs or “pseudofractures").
• Bone mineral density scan (DEXA) may show reduced bone density, a sign of weaker bones.

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

• PTH
• Calcium (ionized
• ALP (alkaline phosphatase isoenzyme