Sun Exposure Not Enough to Correct Vitamin D Deficiency

Kate Johnson

March 17, 2012

March 17, 2012 (San Diego, California) — "The 'epidemic' in vitamin D deficiency is clearly not from too little sun exposure," and dermatologists can be confident in insisting that their patients continue their sun protection efforts, said Richard Gallo, MD, PhD, here at the American Academy of Dermatology (AAD) 70th Annual Meeting.

"Clearly solar exposure is an influence — there is no doubt about that — but you cannot predictably say that a certain amount of exposure will normalize vitamin D deficiency," said Dr. Gallo, chief of dermatology and professor of medicine and pediatrics at the University of California, San Diego, in an interview with Medscape Medical News.

Speaking to an overcapacity audience at the meeting's "Hot Topics" symposium, Dr. Gallo, who was involved in the 2010 Institute of Medicine's (IOM's) consensus report on updated dietary vitamin D intake recommendations, said that although "sunlight is a very reliable source of vitamin D, nutritional sources are clearly required and are, of course, much safer."

He said although there is strong evidence that vitamin D is "absolutely necessary" for bone health, other potential health benefits such as protection from cardiovascular events, cancer, and infection are, as yet, unproven.

Although some physicians advocate universal screening for vitamin D deficiency or insufficiency, Dr. Gallo said there is no evidence to support this approach, and there is a lack of consensus on the definition of these conditions.

The IOM report recommends that patients should have serum vitamin D levels above 20 ng/mL, but the American Endocrine Society sets this level at 30 ng/mL, Dr. Gallo said.

There is evidence to support screening in high-risk individuals, he added, and noted that this is an extensive list including all dark-skinned, pregnant or lactating, elderly, and obese individuals, as well as those with malabsorption syndromes, rickets, osteomalacia, osteoporosis, chronic kidney disease, granulomatous disorders and lymphomas, and patients receiving chronic antifungal therapy.

"This is a pretty broad spectrum of individuals, and it's kind of left up to the individual practitioner right now to use their common sense regarding who should be screened and who shouldn't," Dr. Gallo noted. Physicians who do find a deficiency on screening should consider checking parathyroid hormone, which can sometimes have a compensatory rise, he said.

"An elevated parathyroid hormone paired with low vitamin D and potentially low calcium could be high risk for bone disease. So those kinds of individuals on the severe [low] end you might be best to refer to an endocrinologist," he said in the interview.

"For individuals on the borderline, at 15 ng/mL (and a lot of individuals are there) a simple thing to do is to just suggest a vitamin supplement and rescreen them perhaps 3 to 6 months later."

Winter blood tests will naturally reflect lower levels than in the summer, he added.

Dr. Gallo have disclosed no relevant financial relationships.

American Academy of Dermatology (AAD) 70th Annual Meeting: Presented March 16, 2012.

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