Vitamin D measurement standardization: The way out of the chaos

Substantial variability is associated with laboratory measurement of serum total 25-hydroxyvitamin D [25(OH)D]. The resulting chaos impedes development of consensus 25(OH)D values to define stages of vitamin D status. As resolving this situation requires standardized measurement of 25(OH)D, the Vitamin D Standardization Program (VDSP) developed methodology to standardize 25(OH)D measurement to the gold standard reference measurement procedures...