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Vitamin D Standardization Program (VDSP)

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The National Institutes of Health (NIH) Office of Dietary Supplements (ODS) established the Vitamin D Standardization Program (VDSP) in 2010 and coordinated its efforts until 2018. Part of the ODS Vitamin D Initiative, VDSP is an international collaborative effort to standardize the laboratory measurement of vitamin D status. A standardized laboratory measurement is one that is accurate and comparable over time, location, and laboratory procedure.

Serum total 25-hydroxyvitamin D [25(OH)D] concentration is used to assess an individual’s vitamin D status. Research has consistently shown that there is a great deal of variation in 25(OH)D assays. This assay variation impedes pooling of 25(OH)D results from different studies in systematic reviews for the specific purpose of determining dose-response and/or clinical cutpoints. The VDSP was established to correct this problem.

  • VDSP Goal
    To improve the detection, evaluation, and treatment of vitamin D deficiency and insufficiency by promoting the standardized laboratory measurement of serum total 25-hydroxyvitamin D [25(OH)D]. VDSP promotes the standardized laboratory measurement of total 25(OH)D (a measure of vitamin D status) to improve clinical and public health practice worldwide.
  • VDSP Objectives
    1. Standardize vitamin D measurement in national health surveys worldwide.
    2. Promote standardized 25(OH)D measurement by assay manufacturers and clinical and research laboratories.
    3. Conduct an international research program devoted to 25(OH)D and its laboratory measurement.
  • VDSP Participants
    All VDSP programs are open to assay manufacturers, clinical and commercial laboratories, national survey laboratories, and research laboratories.

Standardized Laboratory Measurement of Total 25(OH)D

A standardized laboratory measurement of 25(OH)D is one that is accurate and comparable to the NIST and Ghent Reference Measurement Procedures (RMPs) over time, location, and laboratory procedure. There are four basic steps necessary to achieve standardization. more

VDSP Reference Measurement System (RMS) Specifics

VDSP developed an RMS to establish the world-wide standardization of 25-hydroxyvitamin D [25(OH)D] measurements. The RMS includes measurement procedures, standard reference materials, CDC certification and/or accuracy-based quality assurance programs, and study designs for standardizing completed studies. more


Commutability is defined as the equivalence of mathematical relationships between results obtained using different measurement procedures for representative samples. The VDSP conducts ongoing commutability studies to establish that the Standardized Reference Materials® (SRMs), and the materials used in accuracy-based performance testing/external quality assessment programs are commutable. more 

Resources and References

A growing number of publications relevant to the VDSP are available. more

Key Collaborating Organizations

Current VDSP collaborators and participating national health and nutrition surveys. more


VDSP News is a free electronic publication that provides updates on the activities of the VDSP and related information. more


A VDSP Meeting was convened November 28-30th, 2017 at the National Institutes of Health in Rockville, MD. The focus of this 2.5-day meeting was to assess the achievements of the Vitamin D Standardization Program (VDSP) based on input from the program’s stakeholders.   

A public meeting to showcase the VDSP’s progress was held on the National Institute of Standards and Technology campus on November 14, 2013. more