Validation of predicted total body water and extracellular water by multi-frequency impedance in young Indonesian adults

To investigate the validity of the prediction of body water compartments by multi-frequency impedance in Indonesians, 42 adults (19 males and 23 females) were recruited in Jakarta, the capital of Indonesia. Extracellular water (ECW) and total body water (TBW) were measured with dilution techniques and predicted from body impedance at 1 and 100 kHz, respectively, using prediction formulas developed in a Dutch population. Furthermore, body weight, body height and body density were measured and as a measure of body build TBW/height and ECW/height were calculated. Percent ECW of body weight in both males (26 +/- 3%) and females (23 +/- 2%) was higher compared to the Dutch reference population, and also the body water distribution (ECW/TBW) was higher (0.46 +/- 0.04) compared to the reference population. TBW/height and ECW/height appeared to be considerably lower in the Indonesian group compared to the reference group, indicating a more slender body shape. TBW was overestimated by 1.8 +/- 2.4 and 2.5 +/- 1.3 kg in males and females, respectively. ECW was underestimated in males by 0.1 +/- 1.2 kg and slightly overestimated in females (0.1 +/- 1.0 kg). After corrections for differences in body build and body water distribution the bias of the predicted TBW was markedly reduced from 2.2 +/- 1.9 to 1.3 +/- 1.8 kg (males and females combined). For ECW the bias after correction for body water distribution and body build was 0.3 +/- 0.6 kg (males and females combined). It is concluded that multi-frequency impedance is suitable for the prediction of body water compartments at the population level but, due to differences in body build and body water distribution, validation in a larger group of Indonesian subjects is needed to avoid systematic prediction errors.