DATE: October 18, 2017
TIME: 8:00 AM PST, 11:00 AM EST

Over the past decade, 25-OH vitamin D has become one of the most common assays requested by physicians.The increase in testing volume has been driven by risk-association studies linking vitamin D not only to calcium homeostasis, but also to cardiovascular disease, stroke, cancer, autoimmune disease, and even fractures.Two major types of assays are used to measure vitamin D – immunoassay and mass spectrometry.  Each of them has its strengths and weaknesses. Measurement is complicated by the existence of two forms of vitamin D (D2 and D3) as well as by the existence of epimers of both forms.  Standardization has only recently been introduced, and proficiency testing, though available, reflects the poor state of the art.  In this session, we will delve into the details of vitamin D measurement, aided by results from a recent study using the first FDA-cleared via the de novo pathway 25-OH vitamin D assay for mass spectrometry. We will discuss ways of acknowledging, and dealing with, limitations of the various assays.

Learning Objectives:

• Understand the need for accuracy in testing total 25-OH-vitamin D
• Evaluate the performance of immunoassay and LC-MS/MS methods for 25-OH vitamin D
• Recognize the importance of standardization efforts in vitamin D
• Identify the challenges of external quality control surveys face in testing accuracy