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Urinary hydroxyproline, creatinine and urea excretion during the growth of five siblings
Insights
This longitudinal study tracked urinary hydroxyproline, creatine, and urea in five siblings over five years. Findings align with cross-sectional data, showing age-related changes and significant fluctuations in excretion levels during childhood development.
Area of Science:
- Biochemistry
- Pediatric Endocrinology
- Human Physiology
Background:
- Longitudinal studies of urinary metabolite excretion in children are crucial for understanding growth and development.
- Previous research primarily relied on cross-sectional data, limiting insights into individual variability.
- Establishing reference ranges for urinary compounds during childhood is essential for clinical and research purposes.
Purpose of the Study:
- To longitudinally assess urinary excretion patterns of hydroxyproline, creatine, and urea in a cohort of siblings.
- To compare these longitudinal findings with existing cross-sectional data in pediatric populations.
- To investigate the relationship between urinary metabolite excretion, growth parameters (height, weight), and pubertal milestones like menarche.
Main Methods:
- Monthly collection of 24-hour urine specimens from five siblings over a five-year period (1971-1976).
- Simultaneous measurement of body height and body weight.
- Analysis of urinary hydroxyproline, creatine, and urea concentrations.
- Calculation of creatinine coefficients to assess excretion variability.
Main Results:
- Urinary excretion levels of hydroxyproline, creatine, and urea showed age-related trends consistent with cross-sectional studies.
- Significant wide fluctuations in excretion levels were observed, even over short periods.
- Creatinine coefficients were not constant, indicating variability in excretion.
- Menarche occurred shortly after the peak of hydroxyproline excretion during puberty.
- The observed hydroxyproline excretion pattern resembled the 'hydroxyproline index' rather than the 'hydroxyproline ratio'.
Conclusions:
- Longitudinal urinary metabolite excretion data in siblings can validate findings from cross-sectional pediatric studies.
- Individual variability in urinary excretion is substantial and requires consideration in clinical assessments.
- The timing of menarche relative to the pubertal hydroxyproline peak provides insights into developmental synchrony.
- The hydroxyproline index appears to be a more relevant indicator of growth-related changes than the hydroxyproline ratio.
Abstract:
Urinary excretions of hydroxyproline, creatine and urea in 24 h specimens from 5 siblings have been determined monthly from 1971 to 1976 together with the measurements of body height and body weight. Changes with age in the urinary levels of these substances are in good agreement with those from cross-sectional studies in various age groups of children. Wide fluctuations of excretion levels occurred. The creatinine coefficients did not remain constant even over short periods. Menarche was observed shortly after the peak of hydroxyproline excretion at puberty. The hydroxyproline excretion pattern is similar to that of hydroxyproline index proposed by Whitehead, and it is quite different from that of hydroxyproline ratio.