Pediatric reference data for lean tissue properties: density and hydration from age 5 to 20 y

Area of Science:

• Pediatric physiology
• Body composition analysis
• Biometrics

Background:

• Hydrometry and densitometry are common methods for assessing pediatric body composition.
• Accuracy relies on valid age- and sex-specific constants for lean tissue hydration and density.
• Empirical data on these constants and their variability are scarce.

Purpose of the Study:

• To measure lean tissue hydration and density in a large pediatric sample.
• To develop new prediction equations for these parameters.
• To compare new values with existing reference data.

Main Methods:

• Utilized a 4-component model to measure body composition in 533 healthy children and adolescents (aged 4-23 years).
• Employed the LMS method to determine age- and sex-specific median values for hydration and density.
• Generated prediction equations using regression analysis based on age, sex, and BMI SDS.

Main Results:

• Observed sex-specific differences in age-associated changes in lean tissue density and hydration.
• Published reference values introduced a mean bias of 2.1% in fat percentage compared to empirical data.
• Age, sex, and BMI SDS were significant predictors; higher BMI SDS correlated with higher hydration and lower density.

Conclusions:

• Lean tissue chemical maturation is nonlinear and sex-dependent.
• Existing reference values for pediatric hydrometry and densitometry are inaccurate and cause significant bias.
• New empirical reference values are provided, highlighting the need for research including diverse ethnic groups.