Vitamin D bụ vitamin ma bụkwa homonụ sterono, nke gụnyere VD2 na VD3, nke a na-akụda ya yiri nke a. A na-agbanwe vitamin D3 na D2 vitamin 25 Hydroxyl vitamin D (gụnyere vitamin 25 na D2). 25- (Oh) VD n'ime ahụ mmadụ, azọda siri ike, dị elu itinye uche. 25- (Oh) VD na-egosipụta mkpokọta vitamin D, yana ike ntụgharị nke vitamin D, yabụ 25- (oh) na-egosi ọkwa nke vitamin D.TE dabere na Immunocromatography ma nwee ike ịnye nsonaazụ n'ime nkeji iri na ise.