The vitamin D epidemic includes deficiency, supplementation, and over-testing

Dec. 21, 2018

From 2000 to 2010, Medicare reimbursements for vitamin D testing increased by 83-fold1—phenomenal increase.

Yet in 2011, the Endocrine Society released guidelines for vitamin D insufficiency, including raising their upper level of insufficiency to 30 ng/mL and including instructions for testing and screening.2

Almost concurrently, the Institute of Medicine (IOM) released their new guidelines for vitamin D supplementation, declaring their own level of deficiency at 20 ng/mL, and tripling the recommended dose for deficient patients,3 adding to the belief that vitamin D insufficiency was more common than previously thought.

But even as supplementation and testing increased, a narrative review published in 20164 indicated there was still a shortage of reliable studies backing up many of the beliefs surrounding vitamin D supplementation.

This creates a tension. Even as recommendations expanded, qualifying more patients as “insufficient,” the evidence for supplementation as a solution was simply not there. Even more concerning, the risks of over-testing are clear and range from pure monetary waste (to the tune of millions of dollars at just one hospital in Maine5), to delays in accurate diagnosis of other issues, to the serious consequences of vitamin D mega dosing, such as increased fractures and mortality.4

So where does this tension originate from? There are many possibilities. First, the guidelines themselves may be partially to blame. For instance, the Endocrine Society guidelines state, “considering that vitamin D deficiency is very common in all age groups and that few foods contain vitamin D, the Task Force recommended supplementation at suggested daily intake and tolerable upper limit levels, depending on age and clinical circumstances.” But this misses the unequivocal statement in the next paragraph: “We do not recommend population screening for vitamin D deficiency in individuals who are not at risk.”

Second, the IOM guidelines give similar advice, showing that average serum concentrations of vitamin D were well above the level for deficiency, regardless of latitude, and stating in equally stark terms that, “Of great concern recently have been the reports of widespread vitamin D deficiency in the North American population. Based on this committee’s work…the concern is not well founded.”

In addition, the two societies also released several papers after the guidelines were published, relating the differences between the two groups’ recommendations.6,7 In these, again, the societies reiterated the same basic points: deficiency is rare and screening should not be done on the general population, and that the non-skeletal benefits of Vitamin D were not proven. Similarly, in 2016 several members of the original IOM committee published yet another article detailing that even the IOM cutoff of 20 ng/mL was too high, and the vast majority of patients had sufficient blood levels.8

Yet, despite the very bodies drafting the guidelines recommending less testing, overtesting is rampant. In 2012-2014, a group at Maine Medical Center found that an average of 23 percent of patients with no indications for vitamin D testing were being tested for vitamin D, with over a third of those being tested multiple times.5 To compound issues, associated diagnosis codes with a third of this testing were for non-specific symptoms that are not associated with deficiency, such as fatigue. All of this totaled an estimated 9.5 million dollars in waste over the two-year span.

So, what are the next steps? As mentioned, the expert opinion panels were in agreement in 2011: routine testing of the general population is simply not advisable. While deficiency may be common compared to other vitamin deficiencies, there is simply no good evidence to suggest testing should be conducted on non-symptomatic patients.

A systematic review by the Agency for Healthcare Research and Quality (US) in 2014 concluded that there was no established evidence linking vitamin D with any symptom outside of bone health,9 and the previously mentioned narrative review published in 20164 concluded similarly, collating evidence that supplementation did not resolve problems that were not associated with bone health. Thus, the benefits of supplementation are limited and yet the dangers of over-supplementation of vitamin D have also been studied, in some cases showing an increase in the exact indices that are being treated such as falling and fracture risks.4

The guidelines and studies have all been rather clear: the healthy population does not need to be screened for vitamin D deficiency. In addition, supplementation above relatively modest levels is unnecessary and possibly harmful. In the end, it is the clinician’s and laboratorian’s duty to push back against unnecessary testing and medication.

 REFERENCES

  1. Shahangian S, Alspach TD, Astles JR, Yesupriya A, Dettwyler WK. Trends in Laboratory Test Volumes for Medicare Part B Reimbursements, 2000–2010. Arch Pathol Lab Med: February 2014, 138(2):189-203.
  2. Holick MF, Binkley NC, Bischoff-Ferrari HA, et al., Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab, 2011, 96(7):1911–1930.
  3. Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium. Dietary reference intakes for calcium and vitamin D. Washington, DC: The National Academies Press (US), 2011.
  4. Allan GM, Cranston L, Lindblad A, et al., Vitamin D: A Narrative Review Examining the Evidence for Ten Beliefs.  J Gen Intern Med, 2016, 31(7):780-791.
  5. Murray KA, Rosen CJ, Hillyer RL, Fairfield KM. Low Value Vitamin D Screening in Northern New England. 5th Annual Lown Institute Conference, 2017.
  6. Rosen CJ, Abrams SA, Aloia JF, Brannon PM, et al., IOM Committee Members Respond to Endocrine Society Vitamin D Guideline. J Clin Endocrinol Metab, 2012, 97(4):1146-1152.
  7. Holick MF, Binkley NC, Bischoff-Ferrari HA, et al., Guidelines for Preventing and Treating Vitamin D Deficiency and Insufficiency Revisited. J Clin Endocrinol Metab, 2012, 97(4):1153-1158.
  8. Manson JE, Brannon PM, Rosen CJ, Taylor CL. Vitamin D Deficiency — Is There Really a Pandemic? N Engl J Med, 2016, 375(19), 1817-1820.
  9. Newberry SJ, Chung M, Shekelle PG, Booth MS, et al., Vitamin D and Calcium: A Systematic Review of Health Outcomes (Update). AHRQ Publication No. 14-E004-EF. Rockville, MD: Agency for Healthcare Research and Quality. September 2014.

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