Aktuelle Ernährungsmedizin 2013; 38 - PP41
DOI: 10.1055/s-0033-1343714

Bioelectrical impedance analysis (BIA) to monitor hydration status of healthy adults

VK Haas 1, M Möwe 2, M Boschmann 1
  • 1Experimental and Clinical Research Center, Charité Universitätsmedizin Berlin, Berlin
  • 2Institut f. Ernährungswissenschaften, Universität Potsdam, Potsdam, Germany

Introduction: Hydration level affects metabolic activity of organs such as liver and muscle [1]. A simple technique to assess hydration is bioelectrical impedance vector analysis (BIVA). So far, BIVA was mainly used under extreme conditions (i.e. height training) or in diseased people (i.e. dialysis or anorexia nervosa patients [2]).

Objectives: The present study aimed at assessing physiological hydration changes under standardized conditions in healthy adults with BIVA.

Methods: We applied single frequency BIA (BIA Corpus Rx4000, Medi-Cal, Karlsruhe, Germany) in 42 healthy adults (20 men, 22 women; age: 36 ± 12 years; BMI: 22.7 ± 4.3 kg/m2) at T1 (screening), T2 (after 12h of fasting and fluid abstention) and at T3 (after controlled rehydration with 500 ml of water). In parallel, we measured urine specific gravity (USG).

Results: Fig. 1 shows BIVA in the group of female participants. All group vector movements took place on the major axis, indicating shifts in hydration. There was no vector movement between T1 and T2. Between T2 and T3, the vector lengthened, indicating a process of relative dehydration and thus the opposite of what we expected. Vice versa USG agreed well with the study protocol (T0, 1.005; T1, 1.011; T2, 1.005 N/m3).

Fig. 1A: Bioelectrical Impedance Analysis in 22 healthy women at baseline (1), and after 12h oft fluid abstention (2)

Fig. 1B: Bioelectrical Impedance Analysis in 22 healthy women after 12h oft fluid abstention (1), and after intake of 500 ml water (2)

Conclusion: The reasons for the discrepant results between BIA and USG when monitoring small changes in hydration are so far not clear. We suspect that the vector movement mapped the exchange between extra- and intracellular fluid space.

References:

[1] Boschmann et al.: Water-Induced Thermogenesis. J ClinEndocrinolMetab88: 6015 – 6019, 2003.

[2] Haas et al.: Bioimpedance and bioimpedance vector analysis in patients with anorexia nervosa. Eur Eat Disord Rev20(5): 400 – 5,2012.

Disclosure of Interest: V. Haas Grant/Research Support from: The Forum Trinkwasser provided financial support in form of an unrestricted grant. All authors were free from commercial influence., M. Möwe: None Declared, M. Boschmann: None Declared