Baseline Assessment of 25-Hydroxyvitamin D Reference Material and Proficiency Testing/External Quality Assurance...

Area of Science:

• Clinical Chemistry
• Laboratory Medicine
• Biochemistry

Background:

• Accurate measurement of total 25-hydroxyvitamin D [25(OH)D] is crucial for assessing vitamin D status.
• Standardization of vitamin D testing requires commutable reference materials and proficiency testing schemes.

Purpose of the Study:

• To evaluate the commutability of reference materials and external quality assessment (EQA) materials for total 25(OH)D measurement.
• To provide guidance for laboratories selecting appropriate quality control materials for vitamin D assays.

Main Methods:

• A 2012 study coordinated by the Vitamin D Standardization Program (VDSP) analyzed 50 serum samples and 17 quality materials.
• Participating laboratories used immunoassay and LC-MS methods for total 25(OH)D analysis.
• Commutability was assessed using materials from NIST, CAP, and the VDSP EQA scheme, following CLSI guidelines.

Main Results:

• The majority of the tested reference and EQA materials demonstrated commutability across different analytical methods.
• This indicates good agreement between laboratory results and the intended measurand for these materials.
• The findings support the reliability of current quality assurance programs for vitamin D testing.

Conclusions:

• Most reference materials are commutable for total 25(OH)D measurement, ensuring reliable vitamin D status assessment.
• The study provides essential data for laboratories to select appropriate reference materials and EQA programs.
• These results form a basis for future VDSP standardization efforts.