Vitamin D bitamin ne kuma hormone ne na steroid, wanda ya haɗa da VD2 da VD3, wanda tsarinsa yayi kama sosai. Ana canza Vitamin D3 da D2 zuwa hydroxyl bitamin D 25 (gami da bitamin D3 da D2 25). 25-(OH) VD a jikin ɗan adam, tsari mai ƙarfi, yawan maida hankali. 25-(OH) VD yana nuna jimlar adadin bitamin D, da ikon canzawar bitamin D, don haka ana ɗaukar 25-(OH) VD a matsayin mafi kyawun ma'auni don kimanta matakin bitamin D. Kayan Binciken ya dogara ne akan immunochromatography kuma yana iya bayar da sakamako cikin mintuna 15.