‘Don’t Screen’ for Vitamin D: New Endo Society Guideline

BOSTON — New Endocrine Society guidelines call for limiting vitamin D supplementation beyond the daily recommended intake to specific risk groups and advises against routine 25-hydroxyvitamin D [25(OH)D] testing in healthy individuals. 

The evidence-based document was presented on June 3, 2024 at the Endocrine Society annual meeting and simultaneously published in the Journal of Clinical Endocrinology and Metabolism. It advises that people who may benefit from vitamin D supplementation include: 

1. Children aged 1-18 years to prevent rickets and to potentially lower the risk for respiratory tract infections
2. Pregnant people to lower the risk for maternal and fetal or neonatal complications
3. Adults older than 75 years to lower the risk for mortality
4. Adults with prediabetes to lower the risk for type 2 diabetes

In those groups, the recommendation is for daily (rather than intermittent) empiric vitamin D supplementation of more than what was recommended in 2011 by the National Academy of Medicine (NAM), which was then called the Institute of Medicine (IOM): 600 IU/d for those aged 1-70 years and 800 IU/d for those older than 70 years. The document acknowledges that the optimal dose for these populations isn’t known, but it provides the dose ranges that were used in the trials cited as evidence for the recommendations. 

In contrast, the document advises against more vitamin D than the recommended daily intake for most healthier adults younger than 75 years and recommends against testing for blood vitamin D levels in the general population, including those with obesity or darker complexions. 

Guideline author Anastassios G. Pittas, MD, professor of medicine at Tufts University School of Medicine, Boston, told Medscape Medical News, “this guideline refers to people who are otherwise healthy, and there’s no clear indication for vitamin D, such as people with already established osteoporosis. This guideline is not relevant to them.”

Pittas also noted, “there’s no single question and single answer about the role of vitamin D in health and disease, which is what people often want to know. There are many questions, and we cannot answer all of them.”

Panel Chair Marie B. Demay, MD, professor of medicine at Harvard Medical School, told Medscape Medical News that indeed the panel was limited by lack of randomized clinical trial evidence to answer many important questions. “There is a paucity of data regarding definition of optimal levels and optimal intake of vitamin D for preventing specific diseases…What we really need are large scale clinical trials and biomarkers so we can predict disease outcome before it happens.”

Overall, Demay said, “The recommendations are that populations adhere to the [NAM/IOM] dietary recommended intakes, and there are certain populations that will likely benefit from levels of intake above [those].” 

Asked to comment, session moderator Clifford J. Rosen, MD, director of Clinical and Translational Research and senior scientist at Maine Medical Center Research Institute, Scarborough, Maine, noted that screening for vitamin D is quite common in clinical practice, but the recommendation against doing so makes sense. 

“When clinicians measure vitamin D, then they’re forced to make a decision what to do about it. That’s where questions about the levels come in. And that’s a big problem. So what the panel’s saying is, don’t screen…This really gets to the heart of the issue, because we have no data that there’s anything about screening that allows us to improve quality of life…Screening is probably not worthwhile in any age group.”

Rosen, who was an author on the 2011 NAM/IOM dietary reference intakes, said that since then, new data have come out regarding the role of vitamin D in mortality in people older than 75 years, benefit in children with regard to respiratory illness, and the potential benefit of vitamin D in pregnancy. “Otherwise, I think we’re going over a lot of the same stuff that we’ve talked about since I was on the IOM panel 15 years ago…But I think the level of evidence and rigor with which they did it is really impressive.”

However, Simeon I. Taylor, MD, professor of medicine at the University of Maryland, Baltimore, expressed disappointment that the document was limited to healthy people. “Although acknowledging challenges in managing vitamin D status in patients with several diseases, [such as] chronic kidney disease or inflammatory bowel disease, the new guidelines do not provide sufficient guidance for practicing physicians about how to manage these complex patients.”

In addition, Taylor said that the guidelines “do not explicitly consider the literature suggesting that alternative testing strategies may provide more relevant insights into vitamin D status. Just as variation in levels of thyroid-binding globulin have convinced endocrinologists not to rely on measurement of total thyroxine; interindividual variation in levels of vitamin D binding protein must be accounted for to interpret measurements of total levels of 25(OH)D. It would have been useful to explicitly consider the possible value of measuring vitamin D binding protein-independent indices of vitamin D status.”

Taylor also raised the same point as an audience member did during the Q&A period regarding patients with osteoporosis or osteopenia. “The value and utility of the new guidelines would be greatly strengthened by providing guidance for how to approach this important and very large group of individuals.”

Taylor did say that the document has “several strengths, including the fact that they acknowledge the major limitations of the quality of relevant evidence derived from clinical trials.” 

In an accompanying commentary, the guideline authors delve into the issues of skin pigmentation and race as they pertain to vitamin D metabolism, writing: 

The panel discovered that no randomized clinical trials have directly assessed vitamin D related patient-important outcomes based on participants’ skin pigmentation, although race and ethnicity often served as presumed proxies for skin pigmentation in the literature. In their deliberations, guideline panel members and selected Endocrine Society leaders underscored the critical need to distinguish between skin pigmentation as a biological variable and race and ethnicity as socially determined constructs. This differentiation is vital to maximize scientific rigor and, thus, the validity of resulting recommendations.

Pittas and Demay have no disclosures relevant to this clinical practice guideline. Rosen has no disclosures. Taylor serves as a consultant for Ionis Pharmaceuticals. 

Miriam E. Tucker is a freelance journalist based in the Washington DC area. She is a regular contributor to Medscape, with other work appearing in The Washington Post, NPR’s Shots blog, and Diatribe. She is on X (formerly Twitter) @MiriamETucker.