VALIDITY OF PREDICTED TOTAL-BODY WATER AND EXTRACELLULAR WATER USING MULTIFREQUENCY BIOELECTRICAL-IMPEDANCE IN AN ETHIOPIAN POPULATION

Total body water (TBW) and extracellular water (ECW) were measured by deuterium oxide dilution and bromide dilution, respectively, in a grou p of 24 male and 20 female healthy Ethiopians, living in the capital A ddis Ababa. Body weight, body height, skinfolds and total body impedan ce at 1 and at 100 kHz were also measured. TBW and ECW were predicted from impedance values at 1 and 100 kHz, respectively, using prediction equations developed in a Dutch adult population. ECW was overestimate d by 1.3 +/- 1.0 kg (p < 0.05) and 0.6 +/- 0.8 kg (p < 0.05) in males and females, respectively. TBW was accurately predicted in males (0.1 +/- 1.9 kg, n.s.), but overestimated in females (1.0 +/- 1.3, p < 0.05 ). TBW/height and ECW/height were substantially lower in the Ethiopian s compared to values recently published in Dutch and Italian adult sub jects, indicating a different, more slender body build of the Ethiopia ns. After correcting for these differences in body build and for the s light differences in body water distribution (ECW/TBW), the difference s between measured and predicted TBW and ECW decreased and were no lon ger significant. The results indicate that the validity of predicted b ody water from impedance depends on the body build of the subjects, wh ich should be taken into account to avoid systematic errors when apply ing prediction formulas from a reference population to another populat ion under study.