From the Department of Medicine, Brigham and Women's Hospital (C.E.P.), Division of Nephrology, Massachusetts General Hospital (J.W., H.T., I.B., R.T.), Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School (A.H.B.), Division of Nephrology, Beth Israel Deaconess Medical Center (D.Z., S.A.K.), and Howard Hughes Medical Institute (D.Z., S.A.K.) - all in Boston; the Laboratory of Epidemiology and Population Sciences, National Institute on Aging, National Institutes of Health, Baltimore (M.K.E., A.B.Z.); the Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD (M.N.); and the Department of Medicine, San Francisco General Hospital and University of California, San Francisco, San Francisco (N.R.P.).
N Engl J Med. 2013 Nov 21;369(21):1991-2000. doi: 10.1056/NEJMoa1306357.
Low levels of total 25-hydroxyvitamin D are common among black Americans. Vitamin D-binding protein has not been considered in the assessment of vitamin D deficiency.
In the Healthy Aging in Neighborhoods of Diversity across the Life Span cohort of blacks and whites (2085 participants), we measured levels of total 25-hydroxyvitamin D, vitamin D-binding protein, and parathyroid hormone as well as bone mineral density (BMD). We genotyped study participants for two common polymorphisms in the vitamin D-binding protein gene (rs7041 and rs4588). We estimated levels of bioavailable 25-hydroxyvitamin D in homozygous participants.
Mean (±SE) levels of both total 25-hydroxyvitamin D and vitamin D-binding protein were lower in blacks than in whites (total 25-hydroxyvitamin D, 15.6±0.2 ng per milliliter vs. 25.8±0.4 ng per milliliter, P<0.001; vitamin D-binding protein, 168±3 μg per milliliter vs. 337±5 μg per milliliter, P<0.001). Genetic polymorphisms independently appeared to explain 79.4% and 9.9% of the variation in levels of vitamin D-binding protein and total 25-hydroxyvitamin D, respectively. BMD was higher in blacks than in whites (1.05±0.01 g per square centimeter vs. 0.94±0.01 g per square centimeter, P<0.001). Levels of parathyroid hormone increased with decreasing levels of total or bioavailable 25-hydroxyvitamin D (P<0.001 for both relationships), yet within each quintile of parathyroid hormone concentration, blacks had significantly lower levels of total 25-hydroxyvitamin D than whites. Among homozygous participants, blacks and whites had similar levels of bioavailable 25-hydroxyvitamin D overall (2.9±0.1 ng per milliliter and 3.1±0.1 ng per milliliter, respectively; P=0.71) and within quintiles of parathyroid hormone concentration.
Community-dwelling black Americans, as compared with whites, had low levels of total 25-hydroxyvitamin D and vitamin D-binding protein, resulting in similar concentrations of estimated bioavailable 25-hydroxyvitamin D. Racial differences in the prevalence of common genetic polymorphisms provide a likely explanation for this observation. (Funded by the National Institute on Aging and others.).
低水平的总 25-羟维生素 D 在非裔美国人中很常见。维生素 D 结合蛋白在维生素 D 缺乏的评估中尚未被考虑。
在黑人及白人的多样性老龄化社区研究队列（2085 名参与者）中，我们测量了总 25-羟维生素 D、维生素 D 结合蛋白和甲状旁腺激素的水平以及骨矿物质密度（BMD）。我们对研究参与者的维生素 D 结合蛋白基因中的两个常见多态性（rs7041 和 rs4588）进行了基因分型。我们在同型合子参与者中估计了生物可利用的 25-羟维生素 D 的水平。
黑人的总 25-羟维生素 D 和维生素 D 结合蛋白水平均低于白人（总 25-羟维生素 D，15.6±0.2ng/ml 比 25.8±0.4ng/ml，P<0.001；维生素 D 结合蛋白，168±3μg/ml 比 337±5μg/ml，P<0.001）。遗传多态性独立地解释了维生素 D 结合蛋白和总 25-羟维生素 D 水平变化的 79.4%和 9.9%。BMD 黑人高于白人（1.05±0.01g/cm²比 0.94±0.01g/cm²，P<0.001）。甲状旁腺激素水平随总 25-羟维生素 D 或生物可利用的 25-羟维生素 D 水平的降低而升高（两种关系均 P<0.001），但在每个甲状旁腺激素浓度五分位中，黑人的总 25-羟维生素 D 水平明显低于白人。在同型合子参与者中，黑人与白人总体上的生物可利用的 25-羟维生素 D 水平相似（分别为 2.9±0.1ng/ml 和 3.1±0.1ng/ml，P=0.71），并且在甲状旁腺激素浓度五分位中也相似。
与白人相比，社区居住的非裔美国人总 25-羟维生素 D 和维生素 D 结合蛋白水平较低，导致估计的生物可利用 25-羟维生素 D 浓度相似。常见遗传多态性在种族中的差异可能解释了这一观察结果。（由美国国立卫生研究院等资助）。
