Current Practice May Over-Diagnose Vitamin D Deficiency

Medical Xpress, November 20, 2013

The current “gold standard” test for measuring vitamin D status may not accurately diagnose vitamin D deficiency in black individuals. In an article in the Nov. 21 New England Journal of Medicine, a team of researchers report finding that genetic differences in a vitamin D carrier protein referred to as D-binding protein may explain the discrepancy between the prevalence of diagnosed vitamin D deficiency in black Americans–based on measuring the molecule 25-hydroxyvitamin D (25OHD)–and a lack of the usual symptoms of vitamin deficiency.

The essential role of vitamin D in maintaining bone health is well recognized, but while measurement of 25OHD alone consistently classifies from 70 to 90 percent of black Americans as vitamin D deficient, the usual consequences of deficiency–such as low  and increased fracture risk–are actually less prevalent among black individuals. That inconsistency led the team led by Ravi Thadhani, MD, MPH, chief of the Division of Nephrology in the Massachusetts General Hospital (MGH) Department of Medicine, to take a closer look at whether current methods accurately determine vitamin D deficiency.

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For the current study, researchers analyzed levels of 25OHD, levels and genetic variants of D-binding protein, and levels of calcium and parathyroid hormone–another marker of vitamin D deficiency–along with bone density readings in almost 1,200 white and around 900 black participants. The results indicated that black participants had significantly lower levels of both 25OHD and D-binding protein, compared with white participants and also showed that about 80 percent of the difference in D-binding protein levels could be explained by genetic variation. However, bone density and calcium levels were higher in black participants, and while their parathyroid hormone levels also were higher, the difference between black and white participants was slight.

“Black people are frequently treated for vitamin D deficiency, but we may not be measuring the right form of vitamin D to make that diagnosis,” says Thadhani, who is senior and co-corresponding author of the NEJM report. “While our finding that 80 percent of black participants in this study met criteria for vitamin D deficiency is consistent with previous studies, we were surprised to find no evidence of problems with bone health. Most vitamin D in the bloodstream is tightly bound to D-binding protein and is not active. When we determined the concentrations of circulating non-bound vitamin D, which would be available to cells, we found that levels of this form were equivalent between black and white participants, which suggested to us that these black individuals may not be truly deficient.”

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  • Reverend Bacon

    Pish tosh! Race is just a social construct. It has no place- and no use- in hard sciences like medicine or economics.

  • JohnEngelman

    “these black individuals may not be truly deficient.”

    – Medical Xpress, November 20, 2013

    I could say something, but I won’t.

  • Spartacus

    Vitamin D is just a social construct. The people who made these tests used bogus science, and they’re only purpose is the establishment of the Fourth Reich.

    • Bossman

      Really?? I guess someone like you has never heard of the disease called Rickets caused by vitamin D deficiency.

      • Reverend Bacon

        The odds are better that “someone like you has never heard of the disease called” Witzelsucht, which is caused by a jocular deficiency.

        • Bossman

          He’s not known for being sarcastic; he’s known for denying the obvious facts.

      • Spartacus

        I guess sarcasm is just too complicated for some people…

        • Bossman

          That sarcasm is not so obvious from someone like you who likes to deny reality. So in your case it is hard to tell when you’re being sarcastic.

      • I would be delighted if more blacks got rickets due to their inability to produce Vitamin D in cloudy lands with short winter days where they do not belong.

        I am northwestern European and northeastern woodland Amerind, and my wife is Japanese, so we are biologically well suited to climates with a genuine change of seasons.

        The original article is really only another essay about what whites are supposed to do for blacks.

  • bigone4u

    Amren is to be congratulated for tracking down these medical stories, which are scattered across the science journals. Someone with appropriate scientific credentials ought to gather the evidence together into a book that laymen could read. Not that the New York Times would review such a book because the evidence is that there are real, significant differences among the races, not just in IQ, but across the board.

  • Laika

    And I should care about anything about blacks, why?

  • Anon

    Typical of medical science and supplements. Look at the wrong disorders, the wrong vitamin and no where near a reasonable dosage.

    The Vitamin D3 thing is important because it has been implicated in obesity and a whole group of problems related to diabetes. Treatment effect starts to happen around 100,000 iu a day for a few weeks.

    • Alexandra1973

      I’ve read that D3 plus K2 (which is found in butter–the yellower the better) helps heal cavities. So when I can afford it I plan on ordering some cod liver + butter oil.

  • Bossman

    USA Blacks may still be deficient in Vitamin D because they are not getting enough sunshine these days. Blacks evolved in hot sunny tropical places.

    • ThatguyinTN

      Maybe they should go back to those hot sunny tropical places then since it would be better for their health and being rid of them would be better for whites health. See its a win-win.

  • If they would go back to Africa, their skin would produce all the vitamin D they need.