Zhu Kun, Hunter Michael, James Alan, Lim Ee Mun, Walsh John P
Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia; School of Medicine and Pharmacology, University of Western Australia, Crawley, Western Australia, Australia.
Busselton Population Medical Research Institute, Busselton, Western Australia, Australia; School of Population Health, University of Western Australia, Crawley, Western Australia, Australia.
Bone. 2015 May;74:146-52. doi: 10.1016/j.bone.2015.01.015. Epub 2015 Jan 31.
Low BMI is a risk factor for osteoporosis, but it is not clear if relationships between BMI, lean mass (LM), fat mass (FM) and BMD are consistent across different levels of BMI. We studied 1929 Caucasian participants (1014 females) aged 45-66years in the Busselton Healthy Ageing Study in Western Australia. Body composition and BMD of total body, lumbar spine, total hip and femoral neck were measured using DXA. From generalized additive models, the positive relationships between BMI and BMD were weaker at high BMI, particularly at the spine and in males. In the entire cohort, adjusting for relevant covariates, LM and FM were significant predictors of all BMD measures in both genders. In men, analysis by tertiles of BMI showed that LM and FM (in kg) were positively associated with BMD (in mg/cm(2)) in tertile 1 except for LM and spine BMD (LM β: 5.18-6.80, FM β: 3.38-9.24, all P<0.05), but not in the middle or upper tertiles (LM β: -3.12-3.07, FM β: -4.75-1.82, P>0.05). In women, LM was positively associated with BMD in each tertile of BMI, except for spine BMD in the upper tertile, with regression coefficients lower in the upper tertile (β: 5.16-9.95, 5.76-9.56 and 2.80-5.78, respectively, all P<0.05). FM was positively associated with total body, spine and total hip BMD in women in BMI tertile 1 (β: 2.86-6.68, P<0.05); these associations were weaker or absent in the middle and upper tertiles. In conclusion, in middle-aged adults the positive relationships between lean or fat mass with BMD among those with higher BMI are absent in males and weaker in females.
低体重指数是骨质疏松症的一个风险因素，但体重指数（BMI）、瘦体重（LM）、脂肪量（FM）和骨密度（BMD）之间的关系在不同BMI水平上是否一致尚不清楚。我们在西澳大利亚州的巴瑟尔顿健康老龄化研究中，对1929名年龄在45 - 66岁的白种人参与者（1014名女性）进行了研究。使用双能X线吸收法（DXA）测量了全身、腰椎、全髋和股骨颈的身体成分和骨密度。从广义相加模型来看，BMI与骨密度之间的正相关关系在高BMI时较弱，尤其是在脊柱部位以及男性中。在整个队列中，调整相关协变量后，瘦体重和脂肪量是男女所有骨密度测量指标的显著预测因素。在男性中，按BMI三分位数进行分析显示，在第一三分位数中，瘦体重和脂肪量（以千克为单位）与骨密度（以毫克/平方厘米为单位）呈正相关，但脊柱骨密度与瘦体重除外（瘦体重β值：5.18 - 6.80，脂肪量β值：3.38 - 9.24，均P<0.05），而在中间或上三分位数中则不然（瘦体重β值： - 3.12 - 3.07，脂肪量β值： - 4.75 - 1.82，P>0.05）。在女性中，瘦体重在BMI的每个三分位数中均与骨密度呈正相关，但上三分位数中的脊柱骨密度除外，上三分位数中的回归系数较低（β值分别为5.16 - 9.95, 5.76 - 9.56和2.80 - 5.78，均P<0.05）。脂肪量在BMI第一三分位数的女性中与全身、脊柱和全髋骨密度呈正相关（β值：2.86 - 6.68，P<0.05）；在中间和上三分位数中，这些关联较弱或不存在。总之，在中年成年人中，BMI较高者中瘦体重或脂肪量与骨密度之间的正相关关系在男性中不存在，在女性中较弱。
