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Evaluation of bioelectrical impedance for prospective nutritional assessment in cystic fibrosis
P C Quirk1, L C Ward, B J Thomas
1Children's Nutrition Research Centre, Royal Children's Hospital, Queensland, Australia.
Insights
Bioelectrical impedance analysis (BIA) effectively predicts changes in total body potassium (TBK) in children with cystic fibrosis. Serial BIA measures can identify undernutrition and poor growth, aiding clinical management.
Area of Science:
- Pediatric Nutrition
- Biomedical Engineering
- Clinical Physiology
Background:
- Cystic fibrosis (CF) is associated with altered body composition and nutritional status.
- Accurate monitoring of nutritional status, particularly total body potassium (TBK), is crucial for managing CF.
- Traditional anthropometry may not fully capture dynamic changes in body composition.
Purpose of the Study:
- To compare bioelectrical impedance analysis (BIA) with anthropometry for predicting changes in total body potassium (TBK) in children with cystic fibrosis.
- To evaluate the utility of serial BIA measurements in identifying suboptimal TBK accretion.
Main Methods:
- A cohort of 31 children with cystic fibrosis was studied.
- Linear regression and analysis of variance were used to compare BIA and anthropometric measures against TBK.
- Children were categorized based on TBK accretion rates (>5%/y vs. <5%/y).
Main Results:
- TBK showed high correlation with height²/impedance, weight, height, and fat-free mass (FFM).
- Changes in TBK correlated moderately with changes in height²/impedance and weight.
- Differences in TBK change between normal and suboptimal accretion groups were detected by impedance and weight changes, but not height or FFM.
Conclusions:
- Serial BIA measurements show promise in predicting progressive undernutrition in children with CF.
- BIA, particularly impedance and weight changes, may be more sensitive than anthropometry for detecting suboptimal growth in CF.
- BIA offers a valuable tool for monitoring nutritional status and growth in pediatric CF patients.
Abstract:
We have compared the use of bioelectrical impedance analysis (BIA) with anthropometry for the prediction of changes in total body potassium (TBK) in a group (n = 31) of children with cystic fibrosis. Linear regression analysis showed that TBK was highly correlated (r > 0.93) with height2/impedance, weight, height, and fat-free mass (FFM) estimated from skin-fold measurements. Changes in TBK were also correlated, but less well, with changes in height2/impedance, weight, height, and FFM (r = 0.69, 0.59, 0.44, and 0.40, respectively). The children were divided into two groups: those who had normal accretion of TBK (> 5%/y) and those who had suboptimal accretion of TBK (< 5%/y). Analysis of variance showed that the significant difference in the change in TBK between the groups was detectable by concomitant changes in impedance and weight but not by changes in height, FFM, or weight and height Z scores. The results of this study suggest that serial BIA measures may be useful as a predictor of progressive undernutrition and poor growth in children with cystic fibrosis.