VOLUME 31, NUMBER 28 THURSDAY, April 20, 2000
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Vitamin D, weak muscles linked

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By Lois Baker
News Services Editor

Adults afflicted with incapacitating muscle weakness and pain may be suffering from an easily treatable vitamin D deficiency, UB endocrinologists have found.

The report, the first to describe cases in the United States of severe myopathy due to a lack of vitamin D, will appear in the April 24 issue of Archives of Internal Medicine.

Paresh Dandona, professor of medicine and director of the Division of Endocrinology, Diabetes and Metabolism for UB and Kaleida Health, reports that five patients confined to wheelchairs because of severe muscle weakness regained normal muscle strength after four to six weeks of vitamin D supplementation. He has treated another five since the report was written.

Vitamin D is produced by the liver in the presence of sufficient calcium and sunlight. Dandona said that myopathy due to vitamin D deficiency has been described for some time in the UK and Northern Europe, owing to the lack of sunshine in those regions.

"Immigrant communities are particularly vulnerable to this condition because of their limited exposure to the sun, their pigmented skin and vegetarian diet," Dandona said. "In addition to osteomalacia (softening of the bones), myopathy is a well-recognized feature of this condition in these regions.

"In the United States, vitamin D deficiency has only recently been appreciated, especially in the northern areas bordering Canada. We see vitamin D deficiency in the hospital setting and in the community at large during the winter months, but in this country, there are no reports of incapacitating muscle weakness associated with vitamin D deficiency."

There is no data on how widespread this syndrome is in the U.S., but Dandona said it is likely quite common in the northern U.S. in persons who, for whatever reason, have little exposure to sunlight, and among those who live where there are long winters and limited sunlight.

The five cases Dandona describes involve a 37-year-old woman with diabetes, a man and woman in their 70s, a 67-year-old woman with cancer, and a 46-year-old woman with a history of psoriasis, joint pain and anorexia nervosa.

All patients were wheelchair-bound and complained of severe muscle pain, weakness and bone tenderness. In each case, the weakness had been attributed to other causes: old age, problems associated with diabetes and general debility.

"The diagnosis in these cases was either masked by the presence of neurological disease or had been totally unrecognized because of its insidious onset," Dandona noted.

His suspicions were raised when patients showed weakness in shoulder and hip-girdle muscles, but not in the limb muscles, a condition known as proximal myopathy. Further tests revealed long-standing vitamin D deficiency in all five patients.

After vitamin D therapy, four patients regained muscle strength and were able to walk without support. The fifth-the patient with anorexia nervosa-was able to stop using a wheelchair and walk with support.

Dandona listed the following conditions that should point to a severe vitamin D deficiency:

- A region with prolonged winters, relative lack of sunshine and limited exposure of the patient
- Body aches and pains, especially in the shins and ribs
- Impaired absorption of nutrients
- Malnutrition, including anorexia nervosa
- Wearing dark clothing for social or religious reasons
- Chronic liver disease.

"The single most important message of this paper is that severe myopathy due to vitamin D deficiency is relatively common, is insidious in onset and once diagnosed, is easy to treat," Dandona said.

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