Value Assignment of Vitamin D Metabolites in Vitamin D Standardization Program Serum Samples
Karen W Phinney1, Johanna E Camara1, Susan S-C Tai1
1National Institute of Standards and Technology, Biomolecular Measurement Division and Chemical Sciences Division, Gaithersburg, MD 20899.
Abstract:
Assay variability has been cited as an obstacle to establishing optimal vitamin D exposure. As part of the Vitamin D Standardization Program (VDSP) effort to standardize the measurement of total 25-hydroxyvitamin D [25(OH)D], the value assignment of total 25(OH)D in 50 single-donor serum samples was performed using two isotope-dilution LC with tandem MS methods. Both methods are recognized as reference measurement procedures (RMPs) by the Joint Committee for Traceability in Laboratory Medicine. These samples and their assigned values serve as the foundation for several aspects of the VDSP. To our knowledge, this is the first time that two RMPs have been used to assign 25(OH)D values to such a large number of serum samples.
Related Concept Videos
01:23Role of Skin in Vitamin D Synthesis
The solar UV B rays (290-315 nm) are absorbed by the skin, and 7-dehydrocholesterol (provitamin D3) photolyzes it to previtamin D3, which undergoes a rapid transformation to vitamin...
01:25Role of Vitamins in Maintaining Bone Health
Vitamin A
Vitamin A is involved in the process of bone remodeling. Retinoic acid, the active metabolite of Vitamin A, has nuclear receptors in osteoblasts and osteoclasts, which are involved in bone remodeling.
Vitamin B12
Vitamin B12 acts as a cofactor during the formation of osteoblast-related proteins, such as osteocalcin. Vitamin B12 plays a role...
01:20Measurement of Bioavailability: Pharmacodynamic Methods