Vitamin D yog cov vitamin thiab tseem yog cov tshuaj steroid, feem ntau suav nrog VD2 thiab VD3, nws cov kev qhia zoo sib xws. Vitamin D3 thiab D2 hloov mus rau 25 hydroxyl vitamin D (xws li 25-dihydroxyl vitamin D3 thiab D2). 25-(OH) VD nyob rau hauv tib neeg lub cev, ruaj khov kev qhia, siab concentration. 25-(OH) VD qhia txog tag nrho cov vitamin D, thiab lub peev xwm hloov pauv ntawm vitamin D, yog li 25-(OH)VD raug suav tias yog qhov ntsuas zoo tshaj plaws rau kev ntsuas qib ntawm cov vitamin D.Cov khoom siv kuaj mob yog ua raws li immunochromatography thiab tuaj yeem muab cov txiaj ntsig tsis pub dhau 15 feeb.