Vitamin D landscape marked by lack of consensus.
Speaker after speaker at a public conference on vitamin D sponsored by the National Institutes of Health acknowledged that there is general disagreement among well-respected scientists and medical organizations not only about recommended intakes, but about whether supplementation of vitamin D (25-hydroxyvitamin D) has any impact on ailments ranging from depression and nonspecific pain to hypertension and fall prevention.
"Most people agree that at least in high-risk individuals with osteoporosis, vitamin D has an impact on bone and skeletal health, but maybe not in those who are asymptomatic or in healthy individuals as a preventive tool," said Dr. Clifford J. Rosen, director of clinical and translational research and a senior scientist at Maine Medical Center Research Institute, Scarborough.
"There seems to be growing evidence that in high-risk individuals, or in those who repeatedly fall, vitamin D may have an impact, particularly in those with very low levels of 25-D."
Other relationships lack conclusive randomized control data, although there are strong observational data for vitamin D's role in preventing type 2 diabetes. Dr. Rosen is one of the investigators in a National Institute of Diabetes and Digestive and Kidney Diseases-funded clinical trial known as D2D, a study of 4,000 IU of vitamin D vs. placebo in high-risk individuals with obesity and prediabetes. The primary outcome is time to onset of type 2 diabetes.
In the meantime, current vitamin D guidance and conclusions differ among leading medical organizations. For example, the American Geriatrics Society (AGS) recommends a daily dose of 4,000 IU for fall prevention in elderly individuals.
This differs from the daily dose for adults recommended by the Endocrine Society (1,5002,000 IU), Institute of Medicine (an average requirement of 400 IU and 600-800 IU meeting the greatest need), and the United States Preventive Services Task Force (600-800 IU as a fall-prevention strategy).
A lack of consensus also exists regarding one's risk of vitamin D deficiency. For example, the AGS puts this risk at less than 30 ng/mL, the Endocrine Society at less than 20 ng/ mL, and the Institute of Medicine at less than 12 ng/mL. "We have a lot of inconsistency in the data," Dr. Rosen concluded. "There's not unanimity in recommendations, even among so-called experts."
During the same session, Dr. Peter Millard presented findings from a national analysis of vitamin D level testing in adult patients conducted from January 2013 to September 2014. The sample, drawn from AthenaHealth's integrated electronic health records, included more than 6,000 internists and family physicians and 2,000 nonphysician clinicians, translating into an estimated 900,000 patient encounters per month.
During that time period 4%-5% of all adult patient encounters were associated with a vitamin D test ordered.
The greatest proportion of tests occurred in patients over the age of 65 (39%) years, and about 70% of all vitamin D tests were conducted in women. Fewer than 0.1% of tests were associated with a diagnosis of osteoporosis. The most common diagnoses associated with ordering of a vitamin D test were depression and falls.
"This was particularly true in the elderly group, where falls became much more important, and depression slightly less," said Dr. Millard, a family physician who practices at Seaport Community Health Center in Belfast, Maine.
Dr. Rosen and Dr. Millard reporting having no financial disclosures.
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