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 and 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 to laboratories 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 two 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 to discuss results as well as methodological issues and advancements in clinically-relevant vitamin D metabolite measurements.
Standard Reference Material (SRM) 972a and SRM 2972
We recommend the use of SRM 972a Vitamin D Metabolites in Human Serum and SRM 2972 25-Hydroxyvitamin D2 and D3 Calibration Solutions at the outset of participation in the QA program to validate methodology and to value-assign in-house control materials. These SRMs may be purchased from the Standard Reference Materials Program at NIST (301-975-2200; fax: 301-948-3730; or e-mail: firstname.lastname@example.org).
VitDQAP Exercise Workshops
VitDQAP Exercise Workshops Workshops are to be held for laboratories that measure vitamin D metabolites in human serum and plasma as part of the QA program. These workshops provide an opportunity for participants to discuss analytical methods, results of the interlaboratory comparison exercises, and other related topics. Our most recent workshop was held at the 2011 Experimental Biology meeting in Washington, DC, on April 13, 2011 as part of the NIST Micronutrients Measurement Quality Assurance Workshop. If you would like more information regarding the workshop, please contact us at email@example.com.
Certificates and Reports
Reports for the first six 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.
NIST/NIH Vitamin D Metabolites Quality Assurance Program