title: Body composition measurement in normal children: ethical and methodological limitations.
abstract: There are significant ethical. practical and theoretical issues that need to be considered when measuring body composition in normal children. For example, when evaluating the use of techniques that involve ionizing radiation, then the benefit to the volunteer subject, or society at large, needs to be balanced against the likely harm to the subject. For children, the detriment per unit dose may be two to three times larger than that for young adults. At present the decision as to the acceptable radiation dose limit for healthy children undergoing research studies remains debatable. Most techniques for measuring body composition require specific validation of their precision and accuracy when used with small subjects; adaptation of existing methods may thus be necessary in order to measure children. In addition, techniques such as densitometry and dual energy X-ray absorptiometry may be impractical for use in young children. A major theoretical issue to be considered is that most body composition techniques assume a constant density or chemical composition of the fat-free mass (FFM). However, the FFM in children does not consist of fixed proportions of water, protein and mineral; rather, the proportions of these change during growth, with water content decreasing and protein and mineral content increasing. Caution must therefore be used in the application of adult-derived body composition constants and equations to children.
authors.affiliation: Department of Medicine (Endocrinology), University of Sydney, NSW, Australia.
authors.forename: L A
authors.initials: LA
authors.lastname: Baur