Vitamin D Level Testing Guidelines

Understanding the Test

The 25-hydroxyvitamin D test is the accepted laboratory measure for determining vitamin D status, though significant variability exists between testing methods and laboratories, according to the American College of Physicians 1, 2
Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has become the gold standard methodology with reference method procedures accepted by the Joint Committee for Traceability in Laboratory Medicine 3

The U.S. Preventive Services Task Force concludes that evidence is insufficient to recommend routine screening in asymptomatic adults, but testing may be considered for patients with specific risk factors, such as low vitamin D intake or decreased absorption, minimal sun exposure, obesity, or darker skin pigmentation 4, 5, 6
Testing may also be considered for patients with bone, endocrine, or autoimmune diseases, which is considered disease management rather than screening 7

Routine screening of asymptomatic, community-dwelling adults without risk factors is not supported by current evidence, with the USPSTF giving this an "I" statement (insufficient evidence) 4

Classification of samples as "deficient" or "nondeficient" can vary by 4% to 32% depending on which assay is used, with testing variability between methods and between laboratories using the same method ranging from 10% to 20% 1, 2, 7, 8
The Centers for Disease Control and Prevention offers the Vitamin D Standardization Certification Program to help laboratories maintain quality and comparability of results 1, 7, 8

Testing in patients with bone, endocrine, or autoimmune diseases should be billed as disease management rather than screening, and vitamin D testing during pregnancy is considered outside the scope of general screening due to unique nutritional demands 7, 8

Despite insufficient evidence for routine screening, testing rates have increased dramatically, with the annual rate of outpatient visits associated with vitamin D deficiency diagnosis more than tripling between 2008 and 2010, and total serum 25-OHD testing increasing by at least 50% year-over-year in more than half of clinical laboratories surveyed in 2009 5, 2, 9