Routine Vitamin D Testing: Unnecessary and Ineffective

A 65-year-old, health-conscious man reports that he eats organic food and exercises regularly. He often asks his family physician for blood tests to assess for “silent abnormalities.” He applies sunscreen whenever he goes outdoors, and at his wellness visit, he asks for a vitamin D test after reading that sunscreen blocks its production in the skin. He takes 1,000 IU of vitamin D₃ as part of a daily multivitamin. His 25-hydroxyvitamin D level is 27 ng per mL (70 nmol per L). [corrected] Although his primary care physician informed him that levels greater than 20 ng per mL (50 nmol per L) are considered adequate for 97.5% of the population, the patient decided to increase his daily vitamin D dose to 5,000 IU and insisted on more frequent checks, every 4 months, until the levels exceed 50 ng per mL (125 nmol per L). [corrected]

His physician explained that high vitamin D levels can be dangerous and that his current dose and level were more than adequate. The patient consulted another clinician who agreed to continue his preferred testing schedule. When the patient presented to his primary care physician 1 year later, he was taking 10,000 IU of vitamin D per day, and his 25-hydroxyvitamin D level was 85 ng per mL (210 nmol per L). [corrected]

Vitamin D Testing Escalation

Over the past 10 years, vitamin D testing has increased worldwide.^1–5 Up to 75% of vitamin D testing is unnecessary, something many researchers have discussed.^6,7 Testing is often patient-driven, promoted in the mass media based on flawed observational data, and performed for inappropriate reasons such as general fatigue.^2,8 The number of vitamin D tests in the United States reimbursed by Medicare Part B increased 83-fold between 2000 and 2010, with many ordered by family physicians.^7,9 The cost of inappropriate testing is estimated at £2 million ($2.5 million) per year and $800 million per year in excess Medicare costs.^2,10 These estimates do not account for downstream costs because abnormal vitamin D test results can result in a cascade of referrals, radiologic tests, and subsequent vitamin D and other laboratory tests.¹⁰

The Value of Vitamin D Supplementation

For years, observational studies suggested a strong correlation between low vitamin D levels and multiple disease states. This led to an assumption of cause and effect between vitamin D and illness and resulted in the initiation of more rigorous randomized studies to evaluate the clinical benefits of vitamin D supplementation. None of these trials were designed to assess the value of vitamin D assessment as a screening test; instead, they measured levels, gave participants supplements or placebo, and then measured outcomes. Baseline vitamin D levels varied across studies, and many studies did not stratify outcomes between patients with very low starting levels and those with higher starting levels. To complicate interpretation, many participants were taking supplements before joining the studies.

The results of these studies are summarized in the U.S. Preventive Services Task Force (USPSTF) 2015 and 2021 recommendation statements and in review articles.^3,10–14 As one article noted, “In almost every trial, various doses and routes of administration did not show efficacy of vitamin D in preventing fractures, falls, cancer, cardiovascular disease, type 2 diabetes mellitus, asthma, and respiratory infections.”¹³