Validation of body composition determination by bioelectrical impedance analysis in acromegaly

Body composition determination by bioelectrical impedance analysis (BIA) has been compared with measurement of total body water (TBW) by tritiated water dilution and estimation of body fat (BF) by measurement of TBW and total body potassium (TBK) in a four-compartment model, in patients with acromegaly. This disorder is accompanied by a profound aberration in body composition. Furthermore TBW and BF were predicted on the basis of anthropometric variables alone. Paired comparisons of TBW estimations by isotope dilution and BIA showed good correlation (Spearman's rank correlation 0.95, P less than 0.01). Isotope dilution resulted in a mean of 1.7 liter (standard deviation 1.87) higher values. Comparison of BF estimations showed also a significant correlation (Spearman's rank correlation 0.75, P less than 0.01), with slightly higher values for BIA (mean 1.4 kg; standard deviation 2.99). BIA improved the prediction of TBW and BF compared with predictions based on anthropometric variables. In a population of acromegalic patients, BIA seemed to be a useful method to estimate TBW and BF.