New vitamin D test promises accurate results

US researchers have developed a new standard for vitamin D testing measuring the serum concentrations of different vitamin D metabolites.

Current methods detect levels of a vitamin D metabolite called 25(OH)D. Measuring vitamin D itself does not work because it is rapidly changed into another form in the liver. However, the test methods that do exist do not always agree and produce different results. To help laboratories come up with consistent and accurate methods, researchers developed a Standard Reference Material called SRM 972, which measures different levels of the vitamin D metabolites 25(OH)D2, 25(OH)D3 and 3-epi-25(OH)D3 in human serum (1) – the latter was previously thought to only exist in the blood of infants but was recently found in adults, too.

The researchers commented that the new reference material would provide a mechanism to ensure measurement accuracy and comparability and represent a first step toward standardization of 25(OH)D measurements. Research suggests vitamin D deficiency or insufficiency may be even more common than previously thought and a risk factor for more than just bone diseases. An estimated 50–75% of people in the US may not be getting enough vitamin D. Low levels of vitamin D have been linked to the development of several conditions, including rickets, osteoporosis, some cancers, multiple sclerosis, and Parkinson’s disease.

1. Phinney K. W. et al. Development and Certification of a Standard Reference Material for Vitamin D Metabolites in Human Serum. Analytical Chemistry. 2012; 84(2):956.