DEQAS was established in 1989. Its objective is to ensure the analytical reliability of 25 hydroxyvitamin D (25OHD) and 1,25 dihydroxyvitamin D (1,25(OH)₂D) assays.

Features include:

·         1200 participants in 54 countries (January 2013)

·         Quarterly distribution of 5 samples of unprocessed human serum

·         25-OHD3, 25-OHD2 values assigned by the CDC Reference Measurement Procedure

·         3-epi-25-OHD3 and 24,25(OH)2D3 values assigned by the CDC routine LC-MS/MS method

·         Separate scheme for 1,25(OH)2D

·         Instant on-line feedback after results submission

·         Archived samples/data available for Researchers

·         Certificates awarded to laboratories meeting the performance targets