title: Estimation of lean body mass in children.
abstract: BACKGROUND
  In adults, dosages of some anaesthetic agents are based on lean body mass (LBM) rather than body weight. Our aim was to derive an equation for estimating LBM in children.
  
  
  METHODS
  Patients comprised three groups: prospective kidney transplant donors from two separate centres (centres 1 and 3) and children referred to a further centre (centre 2) for the routine clinical measurement of glomerular filtration rate (GFR). GFR and extracellular fluid volume (ECV) were measured using Cr-51-EDTA. LBM was directly estimated (eLBM) in adults using an equation based on height and weight. ECV in children was estimated (eECV) from another equation based on height and weight, converted to eLBM using the relationship between eLBM and ECV determined in the adults from centre 1 and then compared with adult data from centre 3.
  
  
  RESULTS
  In children, the ratio of eECV to ECV was 1.04 (SD 0.18). In centre 1, eLBM (kg) was 3.81 (SD 0.55) times greater than ECV (litres) in men (n=50) and 3.77 (0.77) times greater in women (n=51). eLBM in children was therefore derived by multiplying eECV by 3.8. In children, eLBM showed a close linear correlation with measured ECV (eLBM=3.50ECV+2.0; R(2)=0.857), similar to adults (eLBM=2.82ECV+14.5; R(2)=0.582). In all groups, eLBM/weight correlated inversely with weight.
  
  
  CONCLUSIONS
  In terms of the relationships between eLBM, ECV, and weight, children are similar to adults. Therefore, drug dosage in children should also be based on eLBM rather than weight.
authors.affiliation: Department of Nuclear Medicine, Harley St Clinic, London, UK. a.m.peters@bsms.ac.uk
authors.forename: A M
authors.initials: AM
authors.lastname: Peters
authors.forename: H L R
authors.initials: HL
authors.lastname: Snelling
authors.forename: D M
authors.initials: DM
authors.lastname: Glass
authors.forename: N J
authors.initials: NJ
authors.lastname: Bird
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D000777:Anesthetics / Q000008:administration & dosage; D000886:Anthropometry / Q000379:methods; D001827:Body Height / Q000502:physiology; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D004334:Drug Administration Schedule; D045604:Extracellular Fluid / Q000502:physiology; D005919:Glomerular Filtration Rate / Q000502:physiology; D006801:Humans; D007223:Infant; D008875:Middle Aged; D012016:Reference Values; D012727:Sex Characteristics; D055815:Young Adult
chemical_list: D000777:Anesthetics