The urinary C-peptide excretion in normal healthy children

Area of Science:

• Pediatric Endocrinology
• Metabolic Research
• Biomarker Analysis

Background:

• C-peptide is a byproduct of insulin production, reflecting endogenous insulin secretion.
• Understanding C-peptide dynamics in healthy children is crucial for interpreting metabolic status.

Purpose of the Study:

• To establish reference ranges for 24-hour urinary C-peptide excretion in healthy children aged 3-15 years.
• To investigate the relationship between urinary C-peptide and growth parameters.
• To identify age- and sex-specific differences, particularly during puberty.

Main Methods:

• Measured 24-hour urinary C-peptide excretion in 137 healthy children (52 girls, 85 boys).
• Analyzed correlations with age, weight, height, body surface area, and urinary creatinine.
• Used log transformation and linear regression for non-normally distributed data.
• Compared C-peptide excretion between prepubertal and pubertal age groups.

Main Results:

• No significant overall difference in C-peptide excretion between boys and girls.
• Median urinary C-peptide: 0.24 nmol/kg/24 h (range 0.07-0.61 nmol/kg/24 h).
• Positive correlations found between C-peptide and age, weight, height, body surface area, and creatinine.
• Pubertal girls (11-15 yrs) showed higher C-peptide excretion per kg and per body surface area than younger girls (3-10 yrs).
• Pubertal boys (13-15 yrs) showed higher C-peptide excretion per body surface area than younger boys (5-12 yrs).

Conclusions:

• Urinary C-peptide excretion increases with age, weight, and body size in healthy children.
• Children experience increased insulin secretion during their maximal growth spurt, as indicated by elevated urinary C-peptide per body surface area during puberty.