The National Institute of Standards and Technology (NIST) and the National Institutes of Health (NIH) Office of Dietary Supplements (ODS) have established a Vitamin D Metabolites Quality Assurance Program (VitDQAP). Interlaboratory comparison studies are currently directed toward the measurement of 25-hydroxyvitamin D2, 25-hydroxyvitamin D3, and 3-epi-25-hydroxyvitamin D3 in selected serum and plasma matrices as well as method-appropriate control materials. Frozen or freeze-dried serum or plasma samples together with control materials are sent tolaboratories biannually (winter and summer) for analysis. Results are then returned to NIST for data evaluation and tabulation. Value-assignment of the samples is based on the median of all the laboratory results, with confirmation based on measurement at NIST using one or more different methods. Consultation and troubleshooting regarding methods of analysis are also provided. A report of exercise results is sent to participants, and workshops will be scheduled periodically to discuss results as well as methodological issues and advancements in clinically-relevant vitamin D metabolite measurements.
Standard Reference Material (SRM) 972a and SRM 2972a
VitDQAP Exercise Workshops
VitDQAP workshops (or webinars) are held for laboratories that measure vitamin D metabolites in human serumand plasma as part of the QA program. These workshopsprovide an opportunity for participants to discuss analyticalmethods, results of the interlaboratory comparison exercises, and other relatedtopics.
Certificates and Reports
Reports for the first eleven exercises have been published:
An example figure from the Summer 2011 Report illustrating the 25-hydroxyvitamin D (25(OH)DTotal) levels in two study materials as determined by immunoassay (CLIA, EIA and RIA) and LC (LC-MSn and LC-UV) methods is shown below.
Certificates of participation can also be provided upon individual request.
CONFIDENTIALITY STATEMENT: It is our policy that participants' laboratory identification numbers remain confidential and known only to them and ourselves.
How to Join the Program
If you are interested in joining our program, please send an e-mail to firstname.lastname@example.org. There is no fee for participation.