Most people do not know of the problems that exist in accurately measuring vitamin D levels. If they had their blood drawn five times on the same day, they may well get back five different 25(OH)D levels, and the differences could be significant.

4 Responses to Vitamin D blood test: Past and present debates, difficulties, and developments

1. Lynn January 29, 2013 at 7:21 pm

   Has anyone looked at the effect of supplementation timing in relation to test results? I have started having my patients hold their supplemental vitamin D the day of a blood draw, just in case the dose might falsely elevate their blood levels.

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2. John Cannell, MD January 30, 2013 at 12:42 pm

   The half life of 25(OH)D is so long and conversion in the liver is so quick that it does not matter if someone takes D that day of the blood test or not.

   John

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3. JBG February 1, 2013 at 8:54 am

   Progress in 25(OH)D testing has larger potential importance. It is hard to imagine anything that would cause interest in vitamin D to grow as dramatically as a 25(OH)D test as straightforward and cheap as the self blood test used by diabetics.

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4. Rita and Misty February 1, 2013 at 11:43 am

   @JBG…

   I agree with you regarding a self-blood test similar to one used by diabetics…and I think we’ll soon see a 25(OH)D like this…

   However, I think that the 25(OH)D test should be made a standard test, administered as part of one’s yearly physical….IMO–this would certainly cause interest in Vitamin D to increase dramatically.

   Also it would help if the medical community would STOP referring to D as a Vitamin, and rather called what it is: A Pro-Hormone….

   AGAIN: D is a pro-hormone, not a vitamin….

   Just my opinions…

   Rita 🙂

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