title: Normal values for segmental bioimpedance spectroscopy in pediatric patients.
abstract: BACKGROUND
  Localized limb edema is a clinically relevant sign in diseases such as post-thrombotic syndrome and lymphedema. Quantitative evaluation of localized edema in children is mainly done by measuring the absolute difference in limb circumference, which includes fat and fat-free mass. Bioimpedance spectroscopy (BIS) provides information on the fluid volume of a body segment. Our objective was to determine normal ranges for segmental (arm and leg) BIS measurements in healthy children. Additionally, we determined the normal ranges for the difference in arm and ankle circumference and explored the influence of handedness and the correlation between techniques.
  
  
  METHODS
  Healthy children aged 1-18 years were recruited. The ratio of extracellular fluid content between contralateral limbs (estimated as the inter-arm and inter-leg extracellular impedance ratio), and the ratio of extracellular to intracellular fluid content for each limb (estimated as the intracellular to extracellular impedance ratio) were determined with a bioimpedance spectrometer. Arm and ankle circumference was determined with a Gulick II tape.
  
  
  RESULTS
  We recruited 223 healthy children (48 infants, 54 preschoolers, 66 school-aged children, and 55 teenagers). Normal values for arm and leg BIS measurements, and for the difference in arm and ankle circumference were estimated for each age category. No influence of handedness was found. We found a statistically significant correlation between extracellular impedance ratio and circumference difference for arms among teenagers.
  
  
  CONCLUSIONS
  We determined normal BIS ranges for arms and legs and for the difference in circumference between arms and between ankles in children. There was no statistically significant correlation between extracellular impedance ratio and difference in circumference, except in the case of arms in adolescents. This may indicate that limb circumference measures quantities other than fluid, challenging the adequacy of this technique to determine the presence of localized edema in most age groups.
authors: Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
authors: Maria Laura
authors: ML
authors: Avila
authors: School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Brisbane, Australia.
authors: Leigh C
authors: LC
authors: Ward
authors: Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada; Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, ON, Canada.
authors: Brian M
authors: BM
authors: Feldman
authors: Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
authors: Madeline I
authors: MI
authors: Montoya
authors: Child Health Evaluative Sciences, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada; Lawrence S. Bloomberg Faculty of Nursing, University of Toronto, Toronto, Ontario, Canada.
authors: Jennifer
authors: J
authors: Stinson
authors: Department of Research Design and Biostatistics, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.
authors: Alex
authors: A
authors: Kiss
authors: Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
authors: Leonardo R
authors: LR
authors: Brandão
mesh_terms: D000293:Adolescent; D000842:Ankle / Q000033:anatomy & histology; D001132:Arm / Q000033:anatomy & histology; D001834:Body Water / Q000737:chemistry*; D002648:Child; D002675:Child, Preschool; D058266:Dielectric Spectroscopy / Q000295:instrumentation / Q000379:methods*; D045604:Extracellular Fluid / Q000737:chemistry*; D005260:Female; D006801:Humans; D007223:Infant; D007424:Intracellular Fluid / Q000737:chemistry*; D007866:Leg / Q000033:anatomy & histology; D008297:Male; D012016:Reference Values