Nielson Carrie M, Jones Kerry S, Chun Rene F, Jacobs Jon M, Wang Ying, Hewison Martin, Adams John S, Swanson Christine M, Lee Christine G, Vanderschueren Dirk, Pauwels Steven, Prentice Ann, Smith Richard D, Shi Tujin, Gao Yuqian, Schepmoes Athena A, Zmuda Joseph M, Lapidus Jodi, Cauley Jane A, Bouillon Roger, Schoenmakers Inez, Orwoll Eric S
Bone & Mineral Unit (C.M.N., Y.W., C.M.S., E.S.O.), Oregon Health & Science University, Portland, Oregon 97239; School of Public Health (C.M.N., J.L.), Oregon Health & Science University, Portland, Oregon 97239; Medical Research Council Human Nutrition Research (K.S.J., A.P., I.S.), Cambridge, UK CB1 9NL; Department of Orthopedics (R.F.C.), University of California, Los Angeles, California 90095; Pacific Northwest National Laboratory (J.M.J., R.D.S., T.S., Y.G., A.A.S.), Richland, Washington 99354; Institute of Metabolism and Systems Research (M.H.), University of Birmingham, Birmingham, UK B15 2TT; University of California (J.S.A.), Los Angeles, California 90095; School of Medicine (C.M.S., C.G.L., E.S.O.), Oregon Health & Science University, Portland, Oregon 97239; Portland Veterans Affairs Medical Center (C.G.L.), Oregon 97239; Laboratory of Diagnostic Medicine (D.V.), KU Leuven, 3000 Belgium; Laboratory of Clinical and Experimental Endocrinology (D.V., R.B.), KU Leuven, 3000 Belgium; Department of Cardiovascular Sciences (S.P.), KU Leuven, Belgium 3000; Department of Laboratory Medicine (S.P.), University Hospitals Leuven, 3000 Belgium; MRC Keneba (A.P.), Keneba, The Gambia; and Department of Epidemiology (J.M.Z., J.A.C.), University of Pittsburgh, Pennsylvania 15261.
J Clin Endocrinol Metab. 2016 May;101(5):2226-34. doi: 10.1210/jc.2016-1104. Epub 2016 Mar 23.
Total 25-hydroxyvitamin D (25OHD) is a marker of vitamin D status and is lower in African Americans than in whites. Whether this difference holds for free 25OHOD (f25OHD) is unclear, considering reported genetic-racial differences in vitamin D binding protein (DBP) used to calculate f25OHD.
Our objective was to assess racial-geographic differences in f25OHD and to understand inconsistencies in racial associations with DBP and calculated f25OHD.
This study used a cross-sectional design.
The general community in the United States, United Kingdom, and The Gambia were included in this study.
Men in Osteoporotic Fractures in Men and Medical Research Council studies (N = 1057) were included.
Total 25OHD concentration, race, and DBP (GC) genotype exposures were included.
Directly measured f25OHD, DBP assessed by proteomics, monoclonal and polyclonal immunoassays, and calculated f25OHD were the outcome measures.
Total 25OHD correlated strongly with directly measured f25OHD (Spearman r = 0.84). Measured by monoclonal assay, mean DBP in African-ancestry subjects was approximately 50% lower than in whites, whereas DBP measured by polyclonal DBP antibodies or proteomic methods was not lower in African-ancestry. Calculated f25OHD (using polyclonal DBP assays) correlated strongly with directly measured f25OHD (r = 0.80-0.83). Free 25OHD, measured or calculated from polyclonal DBP assays, reflected total 25OHD concentration irrespective of race and was lower in African Americans than in US whites.
Previously reported racial differences in DBP concentration are likely from monoclonal assay bias, as there was no racial difference in DBP concentration by other methods. This confirms the poor vitamin D status of many African-Americans and the utility of total 25OHD in assessing vitamin D in the general population.
血清总25-羟维生素D（25OHD）是维生素D状态的一个标志物，非裔美国人的该指标低于白人。鉴于用于计算游离25OHD（f25OHD）的维生素D结合蛋白（DBP）存在种族遗传差异的报道，尚不清楚这种差异是否适用于游离25OHD。
我们的目的是评估f25OHD的种族地理差异，并了解种族与DBP以及计算所得的f25OHD之间关联的不一致性。
本研究采用横断面设计。
本研究纳入了美国、英国和冈比亚的普通社区。
纳入了男性骨质疏松性骨折研究和医学研究委员会研究中的男性（N = 1057）。
纳入血清总25OHD浓度、种族和DBP（GC）基因型暴露因素。
直接测量的f25OHD、通过蛋白质组学、单克隆和多克隆免疫测定评估的DBP以及计算所得的f25OHD为观察指标。
血清总25OHD与直接测量的f25OHD密切相关（斯皮尔曼r = 0.84）。通过单克隆测定法测量，非裔血统受试者的平均DBP比白人低约50%，而通过多克隆DBP抗体或蛋白质组学方法测量的DBP在非裔血统中并不低。计算所得的f25OHD（使用多克隆DBP测定法）与直接测量的f25OHD密切相关（r = 0.80 - 0.83）。通过多克隆DBP测定法测量或计算得到的游离25OHD，无论种族如何，都反映了血清总25OHD浓度，且非裔美国人低于美国白人。
先前报道的DBP浓度种族差异可能源于单克隆测定偏差，因为其他方法未显示出DBP浓度存在种族差异。这证实了许多非裔美国人维生素D状态不佳，以及血清总25OHD在评估普通人群维生素D方面的实用性。
