Nau K L, Dick A R, Peters K, Schloerb P R
Department of Physical Therapy Education, University of Kansas Medical Center, Kansas City 66160-7601, USA.
J Neurol Sci. 1997 Oct;152 Suppl 1:S36-42. doi: 10.1016/s0022-510x(97)00242-6.
Tracking body composition is necessary to understand how amyotrophic lateral sclerosis (ALS) is affecting a patient's morphology and to provide a basis for appropriate nutritional advice throughout disease progression. Dual X-ray absorptiometry (DEXA) has been shown to reliably detect body composition changes in persons with ALS. However, this procedure is expensive and available primarily for research. The purpose of this study was to determine the relative validity of two common clinical techniques, anthropometry and bioelectrical impedance analysis (BIA), for measuring the body composition of persons with ALS. Twenty-three persons with ALS volunteered for the study; seven with primarily bulbar symptoms, five with primarily arm weakness, five with primarily leg weakness, and six with significant weakness in all extremities. On a single day subjects underwent body composition analysis by the three techniques, with DEXA serving as the criterion method. Anthropometry and BIA results were converted to lean and fat mass using eight prediction equations commonly cited in the literature. Anthropometry measures were also converted to estimates of muscle mass using two additional equations. Both BIA and anthropometry tended to overestimate lean mass and underestimate fat mass compared to DEXA. However, the BIA prediction equations had smaller mean differences, larger correlations, and smaller standard errors of estimate than the anthropometry equations. The Lukaski et al. BIA equation (Lukaski, H.C., Bolonchuk, W.W., Hall, C.B., Siders, W.A., 1986. Validation of tetrapolar bioelectrical impedance method to assess human body composition. J. Appl. Physiol. 60, 1327-1332) most closely matched the values derived by DEXA and is probably the best method for measuring the lean and fat mass of persons with ALS, as long as they maintain adequate hydration levels. The Heymsfield et al. equation (Heymsfield, S.B., McManus, C., Smith, J., Stevens, V., Nixon, D.W., 1982. Anthropometric measurement of muscle mass: revised equations for calculating bone-free arm muscle area. Am. J. Clin. Nutr. 36, 680-690) for estimating muscle mass may also be a useful clinical tool for this population. Further longitudinal studies are needed to determine whether the equations that correlated best with DEXA at a single point in time are also sensitive enough to detect changes in body composition over a period of time.
追踪身体成分对于了解肌萎缩侧索硬化症（ALS）如何影响患者的形态以及为疾病进展全过程提供适当的营养建议依据至关重要。双能X线吸收法（DEXA）已被证明能够可靠地检测ALS患者的身体成分变化。然而，该检查费用高昂且主要用于研究。本研究的目的是确定两种常见临床技术——人体测量法和生物电阻抗分析（BIA）——在测量ALS患者身体成分方面的相对有效性。23名ALS患者自愿参与该研究；其中7名主要表现为延髓症状，5名主要表现为上肢无力，5名主要表现为下肢无力，6名四肢均有明显无力症状。在同一天，受试者通过这三种技术进行身体成分分析，以DEXA作为标准方法。人体测量法和BIA的结果使用文献中常用的8个预测方程转换为瘦体重和脂肪量。人体测量指标还使用另外两个方程转换为肌肉量估计值。与DEXA相比，BIA和人体测量法往往高估瘦体重而低估脂肪量。然而，BIA预测方程的平均差异较小、相关性较大且估计标准误差较小，优于人体测量法方程。卢卡斯基等人的BIA方程（Lukaski, H.C., Bolonchuk, W.W., Hall, C.B., Siders, W.A., 1986. Validation of tetrapolar bioelectrical impedance method to assess human body composition. J. Appl. Physiol. 60, 1327 - 1332）与DEXA得出的值最为接近，可能是测量ALS患者瘦体重和脂肪量的最佳方法，前提是他们保持充足的水合水平。海姆斯菲尔德等人用于估计肌肉量的方程（Heymsfield, S.B., McManus, C., Smith, J., Stevens, V., Nixon, D.W., 1982. Anthropometric measurement of muscle mass: revised equations for calculating bone - free arm muscle area. Am. J. Clin. Nutr. 36, 680 - 690）对于该人群也可能是一种有用的临床工具。需要进一步的纵向研究来确定在某一时刻与DEXA相关性最佳的方程是否也足够敏感，能够检测一段时间内身体成分的变化。
