Screening for Vitamin D Deficiency in Adults

The US Preventive Services Task Force (USPSTF) has recently published recommendations on screening for vitamin D deficiency in adults.

Vitamin D is a fat-soluble vitamin that plays an important role in calcium regulation and bone health. Very few foods naturally contain vitamin D, although in the US many foods are fortified with vitamin D (such as milk, formula, and cereals). Most of the vitamin D the human body uses is made by the skin as a result of exposure to sunlight. After that, vitamin D is processed by the liver and kidney to be useful to the bones.

Vitamin D deficiency results when a person does not get enough vitamin D from the skin (via sun exposure) or food or their liver and/or kidney has problems processing it. Every person has a different level of need for vitamin D, so an exact level of deficiency is difficult to define. Significant vitamin D deficiency can result in bone problems for both children (rickets, osteomalacia) and adults (osteomalacia, osteoporosis). Many studies have suggested links between vitamin D deficiency and a variety of health concerns including depression, falls, fractures, diabetes, heart disease, cancer, and infection; however, many of these links are inconclusive.

Screening for vitamin D is done through a blood test. Measuring a person’s level of total 25-hydroxyvitamin D is currently considered the best indicator of vitamin D status.

This recommendation applies to nonpregnant adults who do not have any signs or symptoms of vitamin D deficiency.

The goal of screening for vitamin D deficiency is to identify and treat it before adverse clinical outcomes occur. However, there is currently not enough evidence to say whether screening for and treating asymptomatic vitamin D deficiency improves any of the health problems described above.

Part of the challenge in interpreting studies is the variable definition of vitamin D deficiency. Screening may misclassify people with vitamin D deficiency because of variability in cutoff values and among different tests. Another rare potential harm of screening is overtreatment with high-dose vitamin D supplements, which can lead to vitamin D toxicity.

Given current evidence, the USPSTF concludes that overall evidence on the benefits of screening for vitamin D deficiency is lacking. Therefore, the balance of benefits and harms of screening for vitamin D deficiency in asymptomatic adults cannot be determined.

Conflict of Interest Disclosures: None reported.