Body Composition Measurements during Infancy

Abstract

Infancy is the period of most rapid postnatal growth and is accompanied by major changes in body composition (BC). There are many challenges to successfully measuring BC of infants in vivo, which include the inherent limitations in the underlying assumptions for each technique. The small body mass and rapid nonuniform changes in body parts, that is, the components of BC during infancy, can strain the technical limits of all methods. Many techniques for in vivo BC measurement used in older people have been applied to infants. However, the vast majority of them either are difficult to adapt for widespread use in infants, or the roles and limitations for using them during infancy are ill‐defined because of limited or no critical validation and cross‐calibration studies. Based on validation data from animals, well‐defined methodological issues in data acquisition and analyses, availability of normative data, and pertinent accuracy and precision of the technique to allow us to determinate clinically relevant changes in BC within a reasonable time interval, three techniques appear to be most suitable for in vivo BC measurement in infants. Anthropometric measurements can be used in field studies or for group comparisons, and total body electrical conductivity (TOBEC) and selected dual‐energy X‐ray absorptiometry (DXA) measurements can be used to compare BC in individual infants. DXA has the advantages of being able to measure bone mass and the potential to be adaptable to the widely available existing instruments. However, regardless of the techniques used in measuring BC in infants, meticulous attention to details in data acquisition and data analysis, and a knowledge of the limitations of the particular technique are the prerequisites for generating valid data.

Comparing apples with apples: it is time for standardized reporting of neonatal nutrition and growth studies

“…It is relatively easy to improve the postnatal weight gain of preterm babies with additional energy in the form of glucose polymers or fat added to enteral feeds, but this may only increase fat mass rather than the intended increase in lean body mass (35,36). At present, simple anthropometric measurements using all three growth parameters and not just weight are the most reliable and readily available growth parameters for preterm babies (37).…”

Bone and Body Composition Measurements of Small Subjects: Discrepancies from Software for Fan-Beam Dual Energy X-Ray Absorptiometry

“…With the older but most widely used pencil beam DXA technique in the study of small subjects, the uncritical acceptance by some investigators of the earlier unvalidated versions of the infant software continues to contribute to the conflicting data in the literature [3,7,8]. Unfortunately, subsequent improvements in the software may not be re-applied to the earlier scans because of differences in scan acquisition technique and non-compatibility of software.…”

“…The development of dual energy X-ray absorptiometry (DXA) with its ability to provide simultaneous measurements of the bone, lean and fat mass components of body composition [3] has increased the ability to understand the interaction between nutrition and growth in research and clinical situations involving animals and humans.…”

DXA Performance in a Pediatric Population: Precision of Body Composition Measurements in Healthy Term-Born Infants Using Dual-Energy X-ray Absorptiometry

“…It has been shown that clothes, diapers, and flannel sheets can interfere with DXA measurements of soft tissues (22) and body weight (23). Work done by Brunton et al (5) showed that increasing the number of flannel sheets consistently increases the DXA determined weight by 33% of the measured blanket weight.…”