Prevalence of 25-hydroxyvitamin D2 in Western New York: A 3-year study

We evaluated the distribution of 25OH-D2 and 25OH-D3 in a general patient population in Western New York to provide insights into how common detectable vitamin D2 is among samples from a general patient population. Serum 25OH-D2 and 25OH-D3 results measured by LC-MS/MS from June 2009 to December 2012 were retrospectively analyzed. A total of 266,269 serum tests were included for analysis. The percentage of tests with 25OH-D2 levels above the assay limit of quantitation (LoQ) decreased from 32% to 17% over the course of the study period. The percentage of tests with 25OH-D2 levels higher than those of 25OH-D3 decreased from 21% to 12%. Sixty-seven percent of the test results with 25OH-D2 levels above the LoQ had serum concentrations of 25OH-D2 higher than those of 25OH-D3. Prevalence of tests with quantifiable 25OH-D2 decreased over time and yet 17% of them still had detectable levels of 25OH-D2, 67% of which had 25OH-D2 levels higher than 25OH-D3. To achieve accurate 25-hydroxyvitamin D measurement, clinical laboratories should assess the accuracy of their assays, and if necessary, determine the local prevalence of 25OH-D2 to determine if mass spectrometry is the platform of choice to assess vitamin D deficiency. •Overall, 25OH-D2 levels in patients were decreasing compared to 25OH-D3.•25OH-D2, despite its gradual decrease, was still detectable in 17% of the patients.•67% of the population who had detectable 25OH-D2 had higher serum 25OH-D2 than 25OH-D3.•Clinical laboratories should assess the accuracy of their assays for both isomers.•If necessary, the local prevalence of 25OH-D2 ought to be determined.