Body mass index versus percentage body fat in Chinese, African-American and Caucasian postmenopausal women

Objective: The aim of the study was to investigate in postmenopausal women whether the relationship between percentage body fat (PBF) and body mass index (BMI) differs between Asians living in Beijing (BA) and African-Americans (AA), and Caucasians (Ca) living in New York City. Methods: Healthy postmenopausal women (231 BA; 113 AA, 95 Ca), aged 50-80 years, were studied. Weight, height and PBF by dual energy X-ray absorptiometry (DXA) were measured. The relationship between PBF and BMI was assessed by multiple regression analysis. Results: Race, reciprocal of BMI (1/BMI) and the interaction between race and 1/BMI were all significantly (P<0.05) related to PBF in this sample. The slope of the line relating 1/BMI to PBF was different for BA compared to AA (P=0.01) and Ca (P=0.003) while the slopes for AA and Ca were not different (P>0.05). At lower levels of BMI, Asians tended to have higher PBF comparable to AA and Ca, while at BMI >30 BA tended to have less PBF than the other groups. Conclusion: The relation between PBF and BMI in BA postmenopausal women differs from that of AA and Ca women in this sample.

中国3-18岁儿童青少年骨密度参照标准：2013-2015年中国儿童青少年心血管健康研究横断面结果

目的骨骼是构成人体的支架，是儿童青少年正常生长发育的基础。人体骨量在20岁左右达到峰值，骨峰值的80％在青少年时期形成。研究证明，峰值骨量决定了中老年的骨量丢失和发生骨质疏松的风险。正确评价儿童的骨密度对于评价正常儿童的生长发育，发现偏移、运动不足及营养相关导致的骨量不足以及继发性（原发病引起和药物引起）骨质疏松具有重要意义。目前，中国没有基于全国数据的儿童青少年骨密度参照标准，本研究旨在建立中国3～18岁儿童青少年骨密度参照值。方法数据来源于2013—2015年中国儿童青少年心血管健康横断面研究，采用双能x线（dualenergyx-ra，absorptiometry，DXA）骨密度仪对7省、自治区、直辖市的10818名3-18岁儿童青少年进行了骨密度检测。采用LMS曲线平滑技术对年龄别傍高别骨密度百分位曲线进行平滑，得出中国3～18岁儿童青少年年龄别／身高别骨密度参照标准。结果东北地区的吉林省儿童青少年平均去头骨密度（totalbodylessheadbonemineraldensity，TBLHBMD）最高，华东地区山东省儿童最低。TBLHBMD随着年龄和身高的增长而增加，男童的TBLHBMD高于女童。与美国儿童TBLHBMD对比发现，不论年龄别、身高别TBLHBMD，美国儿童在每个百分位均高于中国儿童；中美两国儿童身高别TBLHBMD存在很大差异，美国儿童显著高于中国儿童，其中中位数和第3百分位差距最大。结论本研究建立的标准是首个基于中国3-18岁儿童青少年的大样本、广地域人群的骨密度参照标准。以TBLHBMD低于平均水平0～1倍标准差（相当于第51百分位～第15．9百分位）和1～2倍标准差（相当于第15．8百分位～第2．3百分位）作为骨量发育不足和骨量发育严重不足的评价标准，不足者可通过生活方式和饮食干预；以低于2倍标准差（相当于低于第2．2百分位）作为骨量发育异常的评价标准，骨量发育异常者需结合临床进行干预。