Urinary free and conjugated oestrone and oestradiol-17 beta in early infancy

Area of Science:

• Endocrinology
• Pediatric Endocrinology
• Reproductive Biology

Background:

• Estrogens play crucial roles in development and physiological processes.
• Understanding estrogen profiles in infants is vital for assessing normal growth and development.
• Urinary estrogen excretion patterns can serve as biomarkers for endocrine function in early life.

Purpose of the Study:

• To quantify and compare conjugated and free urinary oestrone and oestradiol-17 beta levels in normal male and female infants.
• To investigate the developmental changes in estrogen excretion from early infancy to two years of age.
• To identify potential sex-specific differences in estrogen metabolism during early childhood.

Main Methods:

• Radioimmunoassay (RIA) was employed to measure conjugated and free oestrone and oestradiol-17 beta.
• Urine samples were collected from 44 normal infants (male and female) aged 7 days to 2 years.
• A total of 98 urine samples were analyzed to determine estrogen concentrations.

Main Results:

• Both sexes exhibited significantly higher oestrone and oestradiol-17 beta excretion in the first three months compared to the first year of life.
• Estrogen levels peaked around the second month of infancy.
• During the first seven months, female infants excreted more conjugated oestradiol-17 beta than oestrone, while males excreted equal amounts. Both sexes excreted more free oestrone than oestradiol-17 beta.

Conclusions:

• Urinary estrogen levels in infants undergo significant changes during the first year of life, with a notable peak in early infancy.
• Sex-specific patterns in conjugated estrogen excretion emerge within the first seven months of life.
• These findings contribute to establishing normative data for infant estrogen metabolism and can inform clinical assessments of endocrine health.