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Should healthy, average-risk adults be screened for vitamin D deficiency?
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In average-risk individuals who have no ongoing disease, there is a lack of evidence proving that vitamin D screening is useful.
The U.S. Preventive Services Task Force has addressed this issue and found that there is no direct evidence that links vitamin D screening with clinical outcomes. To be specific, it has not been shown that screening adults for vitamin D deficiency can help prevent osteoporosis, falls, fractures or other conditions that have been linked by association to low vitamin D. Additionally, there is a lack of randomized controlled trials evaluating the risks vs. benefits of vitamin D screening.
Certainly, in high-risk individuals, such as older adults with a history of falls, there are proponents for screening and identifying those with a low vitamin D level, and then supplementing those people to reduce the risk for falls or fractures. However, even that is controversial. As with many routine screenings, a vitamin D measurement tends to lead to more screenings, more measurements and, ultimately, less impact, despite improving the vitamin D level.
There is no harm in conducting a vitamin D screening, other than the cost, which would add up quickly if universal screenings became routine. In a recent study that we conducted here in Maine, 10% of the population with no identifiable diseases or risks underwent a vitamin D screening as a part of their routine exams. That is a lot of money spent, with little to show for it.
Patients often want to do the test — and it is easy to see why. It is easy to have it done, and if the vitamin D level is low, people can be “treated,” meaning, raise the vitamin D level with supplementation, to make people “better.” That provides an opportunity to see if supplementation would be a mechanism that could help the patient. Plus, it is very satisfying for the patient. I do not discount the possibility that vitamin D supplementation might help some people, but as a national policy, screening otherwise-healthy adults would be problematic.
Clifford J. Rosen, MD, is a senior scientist and director of the Center for Clinical and Translational Research at the Maine Medical Center Research Institute. Disclosure: Rosen reports no relevant financial disclosures.
The decision to measure serum 25-hydroxyvitamin D should be individualized according to clinical circumstances.
Vitamin D is an essential nutrient. It is well established that deficiency of vitamin D, with serum 25-(OH)D levels typically less than 10 to 15 ng/mL, causes rickets and osteomalacia. Vitamin D supplementation is generally very safe, although overzealous supplementation may result in symptomatic hypercalcemia in patients with extremely high serum 25-(OH)D levels, usually greater than 150 ng/mL. For patients with symptoms or circumstances associated with vitamin D deficiency or toxicity, there is no doubt that measuring the level is clinically useful.
Given the many uncertainties, controversies, and limited knowledge concerning vitamin D assays, supplementation strategies and clinical benefits, it is risky business to be dogmatic about much else in the vitamin D arena. Although recent and emerging data from placebo-controlled clinical trials, such as VITAL, are expanding our understanding of the effects of vitamin D supplementation, there are limitations that confound extrapolation of the data to the care of individual patients. As an example, in VITAL trial participants, the mean baseline serum 25-(OH)D level was remarkably good at 30.8 ng/mL. By almost any current standard, this level is “sufficient” or “more than sufficient.” It might be expected that there is little, if any, benefit to giving patients more of what they already have enough of, which is what has been reported with regard to risk of invasive cancer and cardiovascular events.
Certainly, patients at high risk for vitamin D deficiency should be tested, as recommended in the Endocrine Society guidelines. Certainly, patients at very low risk should not be tested, consistent with the concept that tests of any kind should only be done when there is a reasonable likelihood that the results would influence clinical decisions or patient behavior. The conundrum lies in the difficulty of recognizing, on clinical grounds alone, patients who are at high risk for vitamin D deficiency. In an NHANES survey of U.S. adults, 41.6% were reported to have serum levels of 20 ng/mL or less. Suffice it to say that vitamin D “deficiency” or “inadequacy” is common and that our threshold for measuring vitamin D should be low. Some patients who appear to be average risk have very low vitamin D levels and are likely to benefit from vitamin D supplementation.
E. Michael Lewiecki, MD, FACP, FACE, is director of the New Mexico Clinical Research and Osteoporosis Center and director of Bone Health TeleECHO at the University of New Mexico Health Sciences Center in Albuquerque. Disclosure: Lewiecki reports no relevant financial disclosures.