Biomaterial Database

Multi-frequency bioelectrical impedance for assessing total body water and extracellular water in elderly subjects. 1995

M Visser, and P Deurenberg, and W A van Staveren

Department of Human Nutrition, Wageningen Agricultural University, The Netherlands.

OBJECTIVE The objective of this study was to investigate the utility of multifrequency bioelectrical impedance for the estimation of total body water (TBW) and extracellular water (ECW) in an elderly population. METHODS Body impedance at 8 frequencies (1-1350 kHz) was measured in duplicate within 1 week. TBW and ECW were determined using deuterium oxide and potassium bromide dilution respectively. METHODS At the Department of Human Nutrition. METHODS 81 women and 36 men, aged 63-87 years, volunteered as subjects. RESULTS Application of prediction equations from the literature, which are mostly based on impedance measurements in young and middle-aged subjects, resulted in large prediction errors of TBW and ECW which were related to the water distribution of the body. New sex-specific prediction equations for the estimation of TBW and ECW were developed for the elderly population and internally validated in random sub-groups. TBW and ECW were best predicted using impedance at frequencies of 5 and 50 kHz respectively, and by using body weight. Prediction errors for TBW were 3.1 kg (7.3%) and 2.7 kg (8.5%) and for ECW 2.2 kg (12.3%) and 1.0 kg (7.4%) for men and women respectively. CONCLUSIONS Multi-frequency impedance measurements are useful to assess TBW and ECW in groups of elderly subjects. However, the prediction errors are larger compared to young and middle-aged subjects, and are related to body water distribution. Individual errors are sometimes unacceptably large.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008875	Middle Aged	An adult aged 45 - 64 years.	Middle Age
D011237	Predictive Value of Tests	In screening and diagnostic tests, the probability that a person with a positive test is a true positive (i.e., has the disease), is referred to as the predictive value of a positive test; whereas, the predictive value of a negative test is the probability that the person with a negative test does not have the disease. Predictive value is related to the sensitivity and specificity of the test.	Negative Predictive Value,Positive Predictive Value,Predictive Value Of Test,Predictive Values Of Tests,Negative Predictive Values,Positive Predictive Values,Predictive Value, Negative,Predictive Value, Positive
D012016	Reference Values	The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.	Normal Range,Normal Values,Reference Ranges,Normal Ranges,Normal Value,Range, Normal,Range, Reference,Ranges, Normal,Ranges, Reference,Reference Range,Reference Value,Value, Normal,Value, Reference,Values, Normal,Values, Reference
D012044	Regression Analysis	Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.	Regression Diagnostics,Statistical Regression,Analysis, Regression,Analyses, Regression,Diagnostics, Regression,Regression Analyses,Regression, Statistical,Regressions, Statistical,Statistical Regressions
D001823	Body Composition	The relative amounts of various components in the body, such as percentage of body fat.	Body Compositions,Composition, Body,Compositions, Body
D001834	Body Water	Fluids composed mainly of water found within the body.	Water, Body
D005110	Extracellular Space	Interstitial space between cells, occupied by INTERSTITIAL FLUID as well as amorphous and fibrous substances. For organisms with a CELL WALL, the extracellular space includes everything outside of the CELL MEMBRANE including the PERIPLASM and the cell wall.	Intercellular Space,Extracellular Spaces,Intercellular Spaces,Space, Extracellular,Space, Intercellular,Spaces, Extracellular,Spaces, Intercellular
D005260	Female		Females
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man