[A comparative study of a bioelectrical impedance method and dual energy X-ray absorptiometry for body composition analysis].

The accuracy of a bioelectrical impedance analysis (BIA) was examined by comparison with a dual energy X-ray absorptiometry (DXA) to measure the body composition. The subjects consisted of 52 patients (21-78y.) with chronic renal failure (32 cases), osteoporosis (6 cases) and diabetes mellitus with obesity (14 cases). Bioelectrical impedance between hand and leg was measured by a body composition analyzer (Model BIA-BC-3, RJL) with a four-electrode system. One pair of current supply and detector electrode was attached to the right hand and another pair was to the leg. The total fat mass measured by BIA was well correlated with the value by DXA (r = 0.959, p < 0.01). The total fat mass by BIA was also correlated with the fat mass in the arms (r = 0.863), fat mass in the legs (r = 0.911), and fat mass in the trunk (r = 0.920) by DXA. The correlation rates were p < 0.01. These correlation coefficients were lower than the correlation rate of the total fat mass measured by DXA. The total lean mass measured by BIA was well correlated with the value by DXA (r = 0.963, p < 0.01). It was correlated with the lean mass in the arms (r = 0.899), lean mass in the legs (r = 0.929), and lean mass in the trunk (r = 0.906) by DXA, but these values were lower than the correlation rate of the total lean mass obtained by DXA. These findings suggest that BIA is a safe and simple method for analyzing the body composition of the total fat mass and the total lean mass, and total body composition is reflected more clearly than regional body composition.