Testing for Vitamin D Deficiency in Veterans-Is There a Seasonal Bias?

Clinicians may have a seasonal bias, favoring testing for vitamin D status in the latter part of the year even though the lowest vitamin D levels are observed in the first part of the year. Although an argument could be made to check for peak 25(OH) vitamin D levels in September and trough levels in March, the seasonal contribution to vitamin D deficiency is overshadowed by ongoing vitamin D deficiency throughout the year. Thus, it may be prudent to test for vitamin D deficiency in patients presenting with fatigue, myalgias, and arthralgias regardless of the season of presentation.