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Published on: August 17, 2022
Total body water in children with cystic fibrosis using bioelectrical impedance
P J Puiman1, P Francis, H Buntain
1School of Medicine, University of Maastricht, Maastricht, The Netherlands.
Insights
Bioelectrical impedance analysis (BIA) underestimates total body water in children with cystic fibrosis (CF). A new prediction equation may improve body composition accuracy in this population.
Area of Science:
- Pediatric Medicine
- Body Composition Analysis
- Bioelectrical Impedance Analysis (BIA)
Background:
- Assessing body composition is crucial for managing pediatric conditions like cystic fibrosis (CF).
- Bioelectrical impedance analysis (BIA) is a non-invasive method for estimating body composition.
Purpose of the Study:
- To evaluate the accuracy of single-frequency BIA in predicting total body water (TBW) in children with CF.
- To develop a specific prediction equation for TBW in this cohort.
Main Methods:
- Compared TBW predicted by BIA with measurements from deuterium oxide dilution in 56 children (aged 4-18 years) with CF.
- Collected urine samples to measure deuterium elimination over 4-6 hours.
Main Results:
- A mean bias of 1.1 L was observed, with BIA underestimating TBW.
- A prediction equation (TBW=0.35+0.74*height²/impedance) was derived, showing consistency with equations for healthy children.
Conclusions:
- Commercially available BIA devices tend to underestimate TBW in children with CF.
- The developed prediction equation may enhance the accuracy of BIA for body composition assessment in pediatric CF patients.
Background:
The aim of this study was to assess the ability of commercially available single frequency bioelectrical impedance analysis (BIA) to predict total body water and hence body composition in a cohort of children with cystic fibrosis (CF).
Methods:
In 56 (31 girls, 25 boys) children aged 4 to 18 years, total body water was predicted using BIA and measured using a deuterium oxide dilution technique. Each child provided a urine sample before consuming 0.5 g/kg body weight 10% deuterium oxide. A further urine sample was collected between 4 and 6 h later.
Results:
There was a mean bias between predicted and measured total body water of 1.1 L. The bias was consistent across the range of total body water measured in this study. The relationship between height2/impedance and measured total body water was TBW=0.35+0.74*height2/impedance. This equation is similar to other equations found in healthy children.
Conclusion:
We have shown that a commercially available bioelectrical device underestimates measured total body water. We have generated a prediction equation for the population studied, which we believe might enhance the accuracy of the method in children with cystic fibrosis.
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