Multicomponent methods: evaluation of new and traditional soft tissue mineral models by in vivo neutron activation analysis1,2,31,2,3

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ABSTRACT

Background:

Practical and accurate methods for quantifying the soft tissue mineral component of multicomponent fat-estimation models are needed.

Objectives:

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 BroΩek and Selinger models) and with criterion estimates based on in vivo neutron activation (IVNA) analysis.

Design:

The subjects were 156 healthy adults and 50 patients with AIDS. Total body potassium, sodium, chlorine, and calcium were measured by IVNA; TBW by 3H2O or D2O 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 BroΩek 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.

KEY WORDS

Extracellular water
intracellular water
body composition
multicomponent methods
neutron activation analysis
soft tissue mineral
AIDS

Cited by (0)

1

From the Department of Medicine, Obesity Research Center, St Luke’s–Roosevelt Hospital, Columbia University, College of Physicians and Surgeons, New York (ZMW, FXP-S, DPK, RNP, and SBH); the Department of Applied Science, Brookhaven National Laboratory, Upton, NY (LW); and the Exercise Physiology Laboratory, Flinders University, Adelaide, Australia (RTW).

2

Supported by National Institutes of Health grant NIDDK 42618.

3

Reprints not available. Address correspondence to ZM Wang, Weight Control Unit, 1090 Amsterdam Avenue, 14th Floor, New York, NY 10025. E-mail: [email protected].