HPLC chromatography system VD-200

UHPLCclinicalUV

Circulating 25-hydroxyvitamin D (25-OH-D) is widely recognized as the best indicator of vitamin D status. In blood circulation the two major vitamin D metabolites are 25-OH Vitamin D3 and 25-OH Vitamin D2. 25-OH-D3 is mainly derived from vitamin D3 produced by sunlight in the skin, while 25-OH-D2 is derived from plants in the diet. There are currently two main types of methods used routinely for measuring 25-OH-D: methods based on chromatographic separation followed by non-immunological direct detection and competitive immunoassays. Most immunoassays depend on an antibody that can detect both 25-OH Vitamin D2 and 25-OH Vitamin D3 together and gives total results. But the proportion of 25-OHD2 detection is variable. Two non-immunological methods for direct detection are currently available: high pressure liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS/ MS). Chromatographic methods are able to measure 25-OH-D2 and 25-OH-D3 independently with excellent accuracy and sensitivity. On the other hand, there is many scientific studies and papers showing inaccuracy measuring total Vitamin D with commercial immunoassays without separating and measuring Vitamin D2 and Vitamin D3 metabolites individually. It is recommended that any 25-OH-D assay in clinical laboratories should measure both 25-OH-D2 and 25-OH-D3 equally in order to report a total 25-OH-D value. The evaluated immunoassays measure total 25-OH-D (both 25-OH-D3 and 25-OH-D2), but the cross-reaction with 25-OH-D2 and 25-OH-D3 differs from 52 to 100% in different methods.