title: An approach to quantifying abnormalities in energy expenditure and lean mass in metabolic disease.
abstract: OBJECTIVE
  The objective of this study was to develop approaches to expressing resting energy expenditure (REE) and lean body mass (LM) phenotypes of metabolic disorders in terms of Z-scores relative to their predicted healthy values.
  
  
  METHODS
  Body composition and REE were measured in 135 healthy participants. Prediction equations for LM and REE were obtained from linear regression and the range of normality by the standard deviation of residuals. Application is demonstrated in patients from three metabolic disorder groups (lipodystrophy, n=7; thyrotoxicosis, n=16; and resistance to thyroid hormone (RTH), n=46) in which altered REE and/or LM were characterised by departure from the predicted healthy values, expressed as a Z-score.
  
  
  RESULTS
  REE (kJ/min) = -0.010 × age (years)+0.016 × FM (kg)+0.054 × fat-free mass (kg)+1.736 (R2 = 0.732, RSD = 0.36 kJ/min). LM (kg)=5.30 × bone mineral content (kg)+10.66 × height2 (m)+6.40 (male). LM (kg)=0.20 × fat (kg)+14.08 × height2 (m)-2.93 (female).(male R2=0.55, RSD = 3.90 kg; female R2 = 0.59, RSD=3.85 kg).We found average Z-scores for REE and LM of 1.77 kJ/min and -0.17 kg in the RTH group, 5.82 kJ/min and -1.23 kg in the thyrotoxic group and 2.97 kJ/min and 4.20 kg in the LD group.
  
  
  CONCLUSIONS
  This approach enables comparison of data from individuals with metabolic disorders with those of healthy individuals, describing their departure from the healthy mean by a Z-score.
authors.affiliation: NIHR/Wellcome Trust Clinical Research Facility, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: L P E
authors.initials: LP
authors.lastname: Watson
authors.affiliation: NIHR/Wellcome Trust Clinical Research Facility, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: P
authors.initials: P
authors.lastname: Raymond-Barker
authors.affiliation: University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrookes Hospital, Cambridge, UK.
authors.forename: C
authors.initials: C
authors.lastname: Moran
authors.affiliation: University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrookes Hospital, Cambridge, UK.
authors.forename: N
authors.initials: N
authors.lastname: Schoenmakers
authors.affiliation: University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrookes Hospital, Cambridge, UK.
authors.forename: C
authors.initials: C
authors.lastname: Mitchell
authors.affiliation: 1] NIHR/Wellcome Trust Clinical Research Facility, Addenbrooke's Hospital, Cambridge, UK [2] MRC-Human Nutrition Research, Elsie Widdowson Laboratory, Cambridge, UK.
authors.forename: L
authors.initials: L
authors.lastname: Bluck
authors.affiliation: University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrookes Hospital, Cambridge, UK.
authors.forename: V K
authors.initials: VK
authors.lastname: Chatterjee
authors.affiliation: University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrookes Hospital, Cambridge, UK.
authors.forename: D B
authors.initials: DB
authors.lastname: Savage
authors.affiliation: 1] NIHR/Wellcome Trust Clinical Research Facility, Addenbrooke's Hospital, Cambridge, UK [2] University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrookes Hospital, Cambridge, UK.
authors.forename: P R
authors.initials: PR
authors.lastname: Murgatroyd
mesh_terms: D000293:Adolescent; D000328:Adult; D001823:Body Composition; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D016014:Linear Models; D008060:Lipodystrophy / Q000503:physiopathology; D008297:Male; D008659:Metabolic Diseases / Q000503:physiopathology*; D008875:Middle Aged; D012737:Sex Factors; D018382:Thyroid Hormone Resistance Syndrome / Q000503:physiopathology; D013971:Thyrotoxicosis / Q000503:physiopathology