Poor correlation between bioelectrical impedance analysis and post illness weight gain in gastroenteritis

Bioimpedance Spectroscopy Imprecisely Assesses Lean Body Mass in Pediatric Dialysis Patients

OBJECTIVES

Alterations in body compositions are strongly associated with poor outcomes in end-stage renal disease patients. Hence, assessment of lean body mass is crucial for clinically monitoring these patients. The use of multifrequency bioimpedance spectroscopy measurements has also been advocated, but their usefulness in children is questioned. We investigated whether their application is appropriate for lean body mass measurement in pediatric patients receiving chronic dialysis.

METHODS

Lean body mass estimates as assessed by multifrequency bioimpedance spectroscopy and by deuterium dilution were obtained for 15 patients (mean age 10.9 ± 3.6 years).

RESULTS

Lean body mass (mean ± standard deviation) determined by bioimpedance was 24.2 ± 10.7 and 24.4 ± 10.3 kg by deuterium technique. Bland-Altman analysis showed a mean (±standard deviation) difference between the 2 methods of -0.25 ± 2.30 kg with 95% limits of agreement of -4.80 to 4.25 kg. In a multiple linear regression model, the hydration status was associated with measurement bias after adjusting for age, sex, weight, and body surface area.

CONCLUSIONS

Our results show a high level of agreement between measurements by bioimpedance and deuterium technique, but the limits of agreement were wide. These findings do not support the use of bioimpedance to individually assess lean body mass in pediatric dialysis patients with and without overhydration.

Bioimpedance and Fluid Status in Children and Adolescents Treated With Dialysis

BACKGROUND

Assessment of hydration status in patients with chronic kidney failure treated by dialysis is crucial for clinical management decisions. Dilution techniques are considered the gold standard for measurement of body fluid volumes, but they are unfit for day-to-day care. Multifrequency bioimpedance has been shown to be of help in clinical practice in adults and its use in children and adolescents has been advocated. We investigated whether application of multifrequency bioimpedance is appropriate for total-body water (TBW) and extracellular water (ECW) measurement in children and adolescents on dialysis therapy.

STUDY DESIGN

A study of diagnostic test accuracy.

SETTING & PARTICIPANTS

16 young dialysis patients (before a hemodialysis session or after peritoneal dialysis treatment) from the Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy, and the Emma Children's Hospital-Academic Medical Center, Amsterdam, the Netherlands.

INDEX TEST

TBW and ECW volumes assessed by multifrequency bioimpedance.

REFERENCE TESTS

TBW and ECW volumes measured by deuterium and bromide dilution, respectively.

RESULTS

Mean TBW volumes determined by multifrequency bioimpedance and deuterium dilution were 19.2±8.7 (SD) and 19.3±8.3L, respectively; Bland-Altman analysis showed a mean bias between the 2 methods of -0.09 (95% limits of agreement, -2.1 to 1.9) L. Mean ECW volumes were 8.9±4.0 and 8.3±3.3L measured by multifrequency bioimpedance and bromide dilution, respectively; mean bias between the 2 ECW measurements was +0.6 (95% limits of agreement, -2.3 to 3.5).

LIMITATIONS

Participants ingested the deuterated water at home without direct supervision by investigators, small number of patients, repeated measurements in individual patients were not performed.

CONCLUSIONS

Multifrequency bioimpedance measurements were unbiased but imprecise in comparison to dilution techniques. We conclude that multifrequency bioimpedance measurements cannot precisely estimate TBW and ECW in children receiving dialysis.