Purpose of review: To provide a state-of-the-art update on some emerging measures of vitamin D status and discuss how assessment of these key vitamin D metabolites might improve prognostication of risk for cardiovascular disease (CVD) outcomes.
Recent findings: Vitamin D deficiency is a highly prevalent condition and relatively easy to treat with supplementation and/or modest sunlight exposure. A substantial body of experimental and epidemiological evidence suggest that vitamin D deficiency is a risk factor for CVD. Most epidemiologic studies to date have focused on total 25-hydroxyvitamin D [25(OH)D] concentrations, which is the established marker of vitamin D stores. However, there is emerging evidence that other novel markers of vitamin D metabolism may better characterize 'true' vitamin D status. Some key novel measures include bioavailable 25(OH)D, free 25(OH)D, 1-25 dihydroxyvitamin D, 24,25-dihydroxyvitamin D3 [24,25(OH)2D3], and ratio of 24,25(OH)2D3 to 25(OH)D [the vitamin D metabolic ratio]. Utilization of these biomarkers may enhance understanding of the association between vitamin D and CVD risk, and may provide explanation for the observation that 25(OH)D is a stronger CVD risk factor in whites than blacks.
Summary: Novel measures of vitamin D status could potentially change clinical practice regarding how patients are currently screened for vitamin D status and defined as vitamin D deficient or not. However, whether measuring any of these alternate markers of vitamin D status can provide further insight regarding CVD risk beyond the traditionally measured 25(OH)D concentrations is uncertain at this time. This is an area where further research is strongly needed.
Keywords: Biomarker; Cardiovascular Risk Factor; Vitamin D.