Archives of Internal Medicine · 1978 · 46 citations · 0 references
MedicineBiochemistryEndocrinologyBone MetabolismHuman NutritionMineral MetabolismVitamin BiochemistryVitamin ChemistryVitamin DVitamin D MetabolismVitamin MetabolismVitamin PhysiologyVitamin D MetabolitesVitamin D Physiology
From intensive work carried out during the past decade, it is clear that vitamin D must be metabolized before it can function.<sup>1</sup>One of the central metabolites in this phenomenon is 25-hydroxyvitamin D<sub>3</sub>(25OHD<sub>3</sub>), to which this publication is devoted. It is also known that 25OHD<sub>3</sub>is metabolized further to an active hormone, 1,25-dihydroxyvitamin D<sub>3</sub>(1,25[OH]<sub>2</sub>D<sub>3</sub>). This report will review the physiology and biochemistry underlying the use of calcifediol (25OHD<sub>3</sub>) in the treatment of disease even in circumstances where there is a lack of 1,25(OH)<sub>2</sub>D<sub>3</sub>. <h3>FUNCTIONS OF VITAMIN D</h3> Vitamin D is unique among the vitamins in the sense that it is a precursor of at least one hormone and, hence, vitamin D<sub>3</sub>must be regarded as a prohormone<sup>1-5</sup>(Fig 1). The numbering system in the molecule is confusing because it is derived from cholesterol, which is