Changes in total body water during adolescent growth

Area of Science:

• Pediatric Endocrinology
• Human Physiology
• Body Composition Analysis

Background:

• Adolescence is a critical period for growth and development, marked by significant changes in body composition.
• Understanding the dynamics of total body water (TBW) during these years is crucial for assessing hydration status and metabolic health.
• Previous research has indicated sex-based differences in body water regulation, but longitudinal data during adolescence is limited.

Purpose of the Study:

• To longitudinally assess changes in total body water (TBW) in adolescent boys and girls over a three-year period.
• To investigate sex-specific differences in the absolute and relative amounts of TBW during puberty.
• To correlate changes in TBW with physical growth parameters like height and weight.

Main Methods:

• A longitudinal study involving 59 boys and 59 girls from junior high and 40 boys and 45 girls from senior high schools.
• Administration of deuterium dioxide (D2O) orally for determination of total body water.
• Analysis of deuterium-to-hydrogen ratios in urine samples using mass spectrometry to calculate TBW.

Main Results:

• Boys exhibited significant increases in both absolute TBW (from 31.9 L to 43.3 L) and relative TBW (from 62.1% to 65.9% by ages 15-16, then 64.2%).
• Girls showed a smaller increase in absolute TBW (from 29.0 L to 31.9 L) but a continuous decrease in relative TBW (from 60.3% to 53.6%).
• Concomitant increases in height and weight were observed in both sexes, with boys showing greater overall changes.

Conclusions:

• Adolescent boys experience a rise in both absolute and relative total body water, aligning with their greater lean mass development.
• Adolescent girls demonstrate a decline in relative total body water, likely due to hormonal influences and increased fat mass deposition.
• These findings highlight distinct patterns of water distribution during male and female pubertal development.