Critical assessment of body-composition measurements in malnourished subjects with Crohn's disease: the role of bioelectric impedance analysis

• Published in: The American journal of clinical nutrition Vol. 59; no. 2; pp. 325 - 330
• Main Authors: Royall, D, Greenberg, GR, Allard, JP, Baker, JP, Harrison, JE, Jeejeebhoy, KN
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 01.02.1994; American Society for Clinical Nutrition; American Society for Clinical Nutrition, Inc
• Subjects: 18O dilution; 40K; Absorptiometry, Photon; Adipose Tissue; AGUA METABOLICA; Analysis of Variance; Anthropometry; AZOTE; bioelectric impedance analysis; Biological and medical sciences; Body Composition; Body Height; Body Water; Bone Density; Crohn Disease - complications; Crohn Disease - pathology; Crohn's disease; dual-energy x-ray absorptiometry; EAU METABOLIQUE; Electric Impedance; ENFERMEDADES INTESTINALES; Female; FEMME; FORMACION OSEA; FORMATION DES OS; Gastroenterology. Liver. Pancreas. Abdomen; HOMBRES; HOMME; Humans; ISOTOPE; ISOTOPOS; MALADIE INTESTINALE; Male; MALNUTRICION; MALNUTRITION; Medical sciences; MUJERES; Nitrogen - analysis; NITROGENO; Nutrition Disorders - etiology; Nutrition Disorders - pathology; Other diseases. Semiology; PESO; POIDS; POTASIO; POTASSIUM; Potassium - analysis; POTENCIAL ELECTRICO; POTENTIEL ELECTRIQUE; PROPIEDADES FISICO-QUIMICAS; PROPRIETE PHYSICOCHIMIQUE; RAYON X; RAYOS-X; Regression Analysis; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus; Crohn's disease; dual-energy x-ray absorptiometry; Body composition; bioelectric impedance analysis; 18O dilution; 40K; Human; Crohn disease; Lean body mass; Digestive diseases; Intestinal disease; Exploration; Malnutrition; Nutritional status; Inflammatory disease; Electrical impedance
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/59.2.325

Bioelectric impedance analysis (BIA) has been widely used for assessment of body composition in healthy subjects but has not been validated in malnourished patients. This study compared calculation of fat-free mass (FFM) by five methods to determine whether the currently used equations for total body water (TBW) as assessed by BIA were applicable to 19 malnourished patients with Crohn's disease. When compared with TBW assessed by H218O dilution, BIA was higher by 5.9 ± 1.1% (P < 0.005). A stepwise-multiple-regression equation was derived to validate BIA: TBW (kg) = 0.25 (ht2/resistance) + 0.29 (wt) + 3.63 (r = 0.97, SEE = 0.28). Comparison of the hydration of FFM (TBW by 18O dilution/FFM) between methods showed that total body potassium (TBK) gave a significantly higher value when compared with the reference method of body protein, mineral, and 18O analysis. Dual-energy x-ray absorptiometry (DXA) provided a value for TBW/FFM in close agreement with the reference method. We conclude that BIA overestimates TBW, and TBK underestimates FFM in malnourished patients. DXA provides an accurate measurement of body fat in malnutrition.