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

Conjugated and free urinary oestrone and oestradiol-17 beta were determined by radioimmunoassay in 98 urine samples of 44 normal male and female infants ranging from 7 days to 2 years of age. Both sexes excreted significantly more oestrone and oestradiol-17 beta during the first 3 months of life compared to the end of the first year. Values peaked at the beginning of the second month. During the first 7 months of life, female infants excreted significantly more conjugated oestradiol-17 beta than oestrone, whereas male infants consistently excreted equal amounts of conjugated oestradiol-17 beta and oestrone. However, both sexes excreted significantly more free unconjugated oestrone than oestradiol-17 beta during the same period.