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Vitamin D Testing: Why it Matters, How it’s Done

Video Transcript

Produced by Quest Diagnostics Incorporated

Participants (in order of appearance)

Vic Salazar
Moderator

Wael Salameh, M.D.
Medical Director, Endocrinology
Quest Diagnostics Nichols Institute
Quest Diagnostics Incorporated

Ronald Swerdloff, M.D.
Professor, Medicine, Endocrinology, Metabolism & Nutrition
UCLA, the University of California
Chief, Division of Endocrinology
Harbor UCLA Medical Center

Richard Reitz, M.D.
Chair, Endocrine Division
Quest Diagnostics Nichols Institute
Quest Diagnostics Incorporated

Scene

The Quest Diagnostics Nichols Institute facility in San Juan Capistrano, California. Quest Diagnostics Nichols Institute is the world renowned esoteric diagnostic research, development and testing operation of Quest Diagnostics, the world’s leading provider of diagnostic testing, information and services.

Video Begins

Vic Salazar

Hello, welcome. I’m Vic Salazar. We are here at Quest Diagnostics Nichols Institute for a discussion about Vitamin D and Vitamin D testing. I’m joined today by three experts in this field. I’d like to introduce them to you. Dr. Wael Salameh is the medical director at Quest Diagnostics. Dr. Ronald Swerdloff, professor of medicine at UCLA, chief of endocrinology at Harbor UCLA Medical Center, and Dr. Richard Reitz, medical director, Quest Diagnostics. Gentlemen, thank you very much for joining me today.

What is Vitamin D

Vic Salazar
There’s been a lot of attention in the media and in scientific journals about Vitamin D. Why is there so much interest in Vitamin D and its effects on one’s health? Dr. Reitz?

Dr. Reitz
Well, Vitamin D has long been recognized as an essential vitamin or hormone if you will. We derive our Vitamin D through sunlight and also through dietary supplements. What has become widely known recently has been the fact that the amount of Vitamin D that we have in our body through either of those two sources is really insufficient. Now we understand that this is most likely the most common deficiency state in the world.

Vic Salazar
Dr. Salameh, what are the different types of Vitamin D that exist?

Dr. Salameh
The Vitamin D that is produced by the body, predominantly by the body is called Vitamin D3, while the Vitamin D that is predominantly supplemented through either Vitamin D supplements or for treatment purposes is called Vitamin D2.

Vic Salazar
Why is Vitamin D important to our bodies?

Dr. Swerdloff
To begin with, what we used to think of as the primary role of Vitamin D was to maintain normal bone health, and if the values of Vitamin D were low, that you had a much increased risk of having osteoporosis or having something that was called osteomalacia, those are weak bone states. Recently, we’ve gained new insights into Vitamin D and we found associations of relatively low levels of Vitamin D that increase your risk of certain other diseases, like heart disease or like cancer or like Diabetes. So our interest in Vitamin D measurement has greatly expanded.

Testing for and Treating Vitamin D Deficiency

Vic Salazar
Let me ask you this. How is Vitamin D tested? Dr. Swerdloff?

Dr. Swerdloff
Well, Vitamin D is measured in blood samples that come from the patient and are collected by the physician or laboratory and sent to an analytical laboratory to measure the amount of that particular vitamin in the blood.

Vic Salazar
Based on the testing results, what would be the therapy that a doctor could prescribe?

Dr. Swerdloff
There are two kinds of doses that are used for Vitamin D medication. One is what we would call a supplementary dose, and that’s what’s given to prevent disease or deficiency. The other is a treatment dose, which is a much larger dose, which is used when there is evidence that there is a medical condition, like bone disease and a chemical evidence of Vitamin D deficiency.

Dr. Reitz
The average person that we assume are normal healthy people walking around may in fact have low levels of the vitamin -- the target level may be mildly low or significantly low. And in the cases where somebody has very low levels of Vitamin D, the physician is most likely is going intervene with pharmacologic treatment over a period of time to bring those levels back up to normal as opposed to taking dietary increase and lots of dietary supplements.

The Type of Test Matters – Vitamin D Testing by Liquid Chromatography Tandem Mass Spectrometry (LC/MS/MS)

Vic Salazar
It’s my understanding there are different tests for Vitamin D. Can you clarify what those tests are?

Dr. Swerdloff
Sure, there are two commonly used tests. One is LC/MS/MS and the other is an immune-based system. They differ in the way that the vitamin is measured. In the LC/MS/MS, a physical method is used to separate the Vitamin D and the Vitamin D components from all the other substances that circulate in the blood and then it’s measured, it’s quantified in terms of how much is present.

In the immunoassay-based method an antibody is created and that antibody recognizes the Vitamin D and then the amount of the Vitamin D is then quantified.

Vic Salazar
You’re saying LC/MS/MS goes deeper into the sample?

Dr. Swerdloff
The LC/MS/MS has the capability of separating the molecules of the substances more reliably and therefore the specificity -- measuring exactly what you want to measure -- is more often accomplished.

Vic Salazar
And how is that helpful for a physician?

Dr. Swerdloff
It is important I think to know whether the Vitamin D that’s measured in the blood for example represents the Vitamin D that is ingested or the Vitamin D that is produced in the body. And the reason for that is that there appears to be different potencies of the two forms of the Vitamin D. And so one can by using this methodology (LC/MS/MS) be able to identify where the Vitamin D that circulates is coming from. And that is a considerable advantage in my view.

Vic Salazar
Dr. Reitz would you like to add to that?

Dr. Reitz
I think that this is important as well because the only form that’s available, that’s commonly used for treatment of deficiency in the United States is the D2, the plant sterol if you will – not what’s made through sunlight in body.

Vic Salazar
What research supports LC/MS/MS as a reliable platform for Vitamin D testing?

Dr. Reitz
There have been several papers that have been published in the literature supporting the utility and reliability of LC/MS/MS measurements for Vitamin D, and as we’ve been talking about this, the fact that there is an increased specificity and there is also an increased sensitivity as well so that one is able to identify very precisely the amount of either component, the naturally occurring D3 or the D2.

Vic Salazar
Do you see LC/MS/MS as the technology of the future?

Dr. Salameh
Yes I do. And I think the specificity of this methodology and its ability to analyze multiple samples in a short period of time with … very good accuracy and very good sensitivity is going to herald a new era in laboratory testing.

Vic Salazar
Gentlemen, this discussion has been educational, it’s been enlightening. Thank you very much for your time. And thank you very much for your interest. I’m Vic Salazar, thanks for joining us.

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