Vitamin D testing is commonly used to classify Vitamin D insufficiency. Vitamin D testing often refers to quantitating 25-hydroxyvitamin D, also known as 25-OH vitamin D. Although the active form of Vitamin D is 1,25-dihydroxyvitamin D, most vitamin D is found in its storage forms, 25-OH vitamin D2 and D3, at levels up to 1,000-fold higher and with a longer half-life than the active form.1
25-OH Vitamin D assay kits are subject to interference from many sources, from Vitamin D metabolites, to common dietary supplements.2 The Centers for Disease Control and Prevention (CDC) has established the liquid chromatography–tandem mass spectroscopy (LC-MS/MS) method as the reference method for 25-OH Vitamin D testing. This method eliminates interferences and measures only the relevant fractions, ergocalciferol (D2) and cholecalciferol (D3).3,4 The Cascadion SM 25-Hydroxy Vitamin D assay uses gold standard mass spectrometry for 25-OH Vitamin D testing.
Learn more about Vitamin D test kits and methods