title: Multicomponent methods: evaluation of new and traditional soft tissue mineral models by in vivo neutron activation analysis.
abstract: BACKGROUND
  Practical and accurate methods for quantifying the soft tissue mineral component of multicomponent fat-estimation models are needed.
  
  
  OBJECTIVE
  The aims were to develop a new complete model for estimating soft tissue minerals based on measured total body water (TBW) and extracellular water (ECW) and a simplified new model based on TBW measurements only and to compare these estimates with those determined with 2 traditional models (ie, the Brozek and Selinger models) and with criterion estimates based on in vivo neutron activation (IVNA) analysis.
  
  
  METHODS
  The subjects were 156 healthy adults and 50 patients with AIDS. Total body potassium, sodium, chlorine, and calcium were measured by IVNA; TBW by (3)H(2)O or D(2)O dilution; ECW by bromide dilution; and bone mineral by dual-energy X-ray absorptiometry.
  
  
  RESULTS
  The mean (+/- SD) mass of total-body soft tissue minerals in healthy adults was 467 +/- 62 g with the IVNA model, 492 +/- 62 g with the new model, and 487 +/- 59 g with the simplified new model. Compared with the IVNA model, the complete and simplified new models overestimated soft tissue minerals by 5.4% and 4.6% (both P < 0.001), respectively. In contrast, the Brozek and Selinger models overestimated overall mean soft tissue minerals by 35% and 99% (both P < 0.001), respectively. Overall results for soft tissue mineral prediction with the 2 new models were less satisfactory for the patients with AIDS, although the results were better than those with the traditional models.
  
  
  CONCLUSIONS
  The physiologically formulated complete new model for estimating soft tissue minerals provides the opportunity to upgrade the accuracy of current multicomponent models for estimating total body fat.
authors.affiliation: Department of Medicine, Obesity Research Center, St Luke's-Roosevelt Hospital, Columbia University, College of Physicians and Surgeons, New York, NY, USA. zw28@columbia.edu
authors.forename: ZiMian
authors.initials: Z
authors.lastname: Wang
authors.forename: F Xavier
authors.initials: FX
authors.lastname: Pi-Sunyer
authors.forename: Donald P
authors.initials: DP
authors.lastname: Kotler
authors.forename: Lucian
authors.initials: L
authors.lastname: Wielopolski
authors.forename: Robert T
authors.initials: RT
authors.lastname: Withers
authors.forename: Richard N
authors.initials: RN
authors.lastname: Pierson
authors.forename: Steven B
authors.initials: SB
authors.lastname: Heymsfield
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000378:metabolism; D000328:Adult; D001823:Body Composition; D001834:Body Water / Q000737:chemistry; D005110:Extracellular Space / Q000737:chemistry; D006801:Humans; D007424:Intracellular Fluid / Q000737:chemistry; D008875:Middle Aged; D008903:Minerals / Q000032:analysis*; D008954:Models, Biological; D009501:Neutron Activation Analysis; D012016:Reference Values
chemical_list: D008903:Minerals