Estradiol levels and secretory dynamics in normal girls and boys as determined by an ultrasensitive bioassay: a 10 year experience.

We utilized an ultrasensitive recombinant cell bioassay to measure serum estradiol in 800 normal children from birth through puberty. 105 children had repeat samples every 4 months as they approached puberty. We measured estradiol levels every hour for 24 hours in 55 children. Estradiol increased with age and pubertal stage in girls and boys, and was higher in girls than boys at each stage. Prepubertal girls have estradiol levels of 1.6 +/- 2.6 pg/ml. Prepubertal boys have estradiol levels of 0.4 + 1.1 pg/ml. Estradiol had a diurnal variation in girls and boys, with the trough occurring 08.00-20.00 h in girls, and 12.00-20.00 h in boys. We confirm that estradiol levels are higher in girls than boys even before physical signs of puberty, and that estradiol increases throughout puberty in girls and boys. This 10-year experience in 800 children shows the range and variability of estradiol by an ultrasensitive bioassay.