I-Vitamin D iyi-vitamin futhi iyi-hormone ye-steroid, ikakhulukazi ehlanganisa i-VD2 ne-VD3, ukwakheka kwayo kufana kakhulu. I-Vitamin D3 ne-D2 ziguqulwa zibe yi-25 hydroxyl vitamin D (kufaka phakathi i-25-dihydroxyl vitamin D3 ne-D2). I-25-(OH) VD emzimbeni womuntu, ukwakheka okuzinzile, ukuhlushwa okuphezulu. I-25-(OH) VD ibonisa inani eliphelele le-vitamin D, kanye nekhono lokuguqula i-vitamin D, ngakho-ke i-25-(OH)VD ibhekwa njengesibonakaliso esihle kakhulu sokuhlola izinga le-vitamin D. I-Diagnostic Kit isekelwe ku-immunochromatography futhi inganikeza umphumela zingakapheli imizuzu eyi-15.