Vitamin D Reference Method Laboratory

The Vitamin D Reference Method Laboratory uses a unique, highly accurate and precise reference method. The method provides reference measurements for total 25-hydroxyvitamin D (sum of 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3) in serum.

CDC’s reference method for total 25-hydroxyvitamin D uses high-performance liquid chromatography coupled with tandem mass spectrometry. It separately quantitates 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3. The method has a high level of specificity and is not affected by other vitamin D isomers, such as C3-epi-25-hydroxyvitamin D3.

This reference method meets stringent analytical performance criteria (maximum allowable bias: ≤1.7%; maximum allowable imprecision: ±5%). This ensures that measurement results are highly certain and can be used to assess the measurement accuracy of clinical vitamin D tests.

The reference method is calibrated using certified reference material (SRM 2972a from the National Institute of Standards and Technology [NIST] ). Therefore, measurement results obtained with this reference method are traceable to the International System of Units (SI) , in accordance with the International Organization for Standardization (ISO) standard for traceability in laboratory medicine.