Assessment and interpretation of circulating 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D in the clinical environment

Abstract

The unique cis-triene structure of vitamin D and related metabolites makes it susceptible to oxidation, ultraviolet (UV) light-induced conformational changes, heat-induced conformational changes, and attacks by free radicals. Vitamin D(2) is much less bioactive than vitamin D(3) in humans. Metabolic activation and inactivation of vitamin D are well characterized and result in a plethora of metabolites, of which only 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)(2)D) provide any clinically relevant information. 25(OH)D(2) and 25(OH)D(3) are commonly known as calcifediol and the 1,25(OH)(2)D metabolites as calcitriol. In this review the current state of the science on the clinical assessment of circulating 25(OH)D and 1,25(OH)(2)D is described.

Copyright 2010 Elsevier Inc. All rights reserved.

Figures

Fig. 1

Elevations in plasma total 25(OH)D in volunteers following supplementation with vitamin D2 as measured by the DiaSorin Liaison Total method versus HPLC. Volunteers were given vitamin D2. Presupplementation concentrations are represented by the closed boxes and postsupplementation by the closed diamonds.