Vitamin D is a vitamin and is also a steroid hormone, mainly including VD2 and VD3, whose struction is very similar. Vitamin D3 and D2 are converted to 25 hydroxyl vitamin D(including 25-dihydroxyl vitamin D3 and D2). 25-(OH) VD in the human body, stable struction, high concentration. 25-(OH) VD reflects the total amount of vitamin D , and the conversion ability of vitamin D, so 25-(OH)VD is considered to be the best indicator for evaluating the level of vitamin D.The Diagnostic Kit is based on immunochromatography and can give a result within 15 minutes.