Value Assignment of Vitamin D Metabolites in Vitamin D Standardization Program Serum Samples

Area of Science:

• Clinical Chemistry
• Analytical Chemistry
• Endocrinology

Background:

• Assay variability in 25-hydroxyvitamin D [25(OH)D] measurement hinders optimal vitamin D status assessment.
• Standardization of vitamin D measurements is essential for accurate clinical interpretation and public health guidance.

Purpose of the Study:

• To standardize the measurement of total 25-hydroxyvitamin D [25(OH)D] as part of the Vitamin D Standardization Program (VDSP).
• To assign accurate values to 50 serum samples using validated reference measurement procedures.

Main Methods:

• Utilized two isotope-dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods.
• Employed methods recognized as reference measurement procedures (RMPs) by the Joint Committee for Traceability in Laboratory Medicine.
• Assigned values to 50 single-donor serum samples.

Main Results:

• Successfully assigned 25(OH)D values to 50 serum samples.
• Demonstrated the feasibility of using two RMPs for value assignment in a large sample set.
• Established a foundational set of characterized samples for the VDSP.

Conclusions:

• The use of two RMPs provides a robust approach for standardizing 25(OH)D measurements.
• This study represents a significant advancement in vitamin D measurement standardization.
• The characterized serum samples will support ongoing VDSP efforts and improve vitamin D testing accuracy.