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Clin Chem. 2015 Jun;61(6):877-84. doi: 10.1373/clinchem.2015.240051. Epub 2015 Apr 28.

24,25-Dihydroxyvitamin d3 and vitamin D status of community-dwelling black and white Americans.

Author information

1
Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA; ahberg@bidmc.harvard.edu rthadhani@mgh.harvard.edu.
2
Division of Endocrinology, Massachusetts General Hospital, Boston, MA;
3
Laboratory of Epidemiology and Population Sciences, National Institute on Aging, National Institutes of Health, Baltimore MD;
4
Division of Nephrology, Massachusetts General Hospital, Boston, MA;
5
Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA;
6
Department of Medicine, San Francisco General Hospital and University of California, San Francisco, CA;
7
Division of Nephrology, Beth Israel Deaconess Medical Center, Boston, MA; Howard Hughes Medical Institute, Chevy Chase, MD.
8
Division of Nephrology, Massachusetts General Hospital, Boston, MA; ahberg@bidmc.harvard.edu rthadhani@mgh.harvard.edu.

Abstract

BACKGROUND:

24,25-Dihydroxyvitamin D [24,25(OH)2D] is a metabolite of 25-hydroxyvitamin D (25D). Blacks frequently have low total 25D without manifestations of vitamin D deficiency, suggesting that total serum 25D may incorrectly reflect vitamin D status in different racial groups. The ratio of serum 24,25(OH)2D to 25D [vitamin D metabolite ratio (VMR)] represents a new candidate biomarker for vitamin D status.

METHODS:

We measured 24,25(OH)2D3 and 25D3 by mass spectrometry in a random community cohort of black (n = 212) and white (n = 164) Americans to evaluate VMR as a marker for vitamin D status. We measured parathyroid hormone concentrations by immunoassay to compare VMR and 25D3 against a physiological indicator of vitamin D deficiency.

RESULTS:

Serum 24,25(OH)2D3 strongly correlated with 25D3 in both black and white study participants (r = 0.90, P < 0.001 and r = 0.86, P < 0.001 respectively). Blacks had lower mean 25D3 than whites [17.0 (7.8) vs 27.5 (11.3) ng/mL; 42.4 (19.5) vs 68.6 (28.2) nmol/L, P < 0.001] and lower mean 24,25(OH)2D3 [2.1 (1.3) vs 3.6 (2.0) ng/mL; 5.1 (3.1) vs 8.7 (4.8) nmol/L, P < 0.001]. In contrast to total 25D3 concentrations, mean VMR values were similar in blacks and whites [11.9 (4.0) vs 12.5 (3.4), P = 0.16, respectively] and were negatively correlated with parathyroid hormone concentrations in both races (rs = -0.26, P < 0.001, and rs = -0.25, P < 0.001, respectively).

CONCLUSIONS:

Our results provide further evidence that measurement of total 25D for assessment of vitamin D status in patients of African descent deserves reevaluation and suggest that alternative measures such as VMR should be considered.

PMID:
25922442
PMCID:
PMC4686255
DOI:
10.1373/clinchem.2015.240051
[Indexed for MEDLINE]
Free PMC Article

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