Circulating bound and free estradiol and estrone during normal growth and development and in premature thelarche and isosexual precocity.

Serum concentrations of unconjugated estrone, estradiol, and free estradiol, were determined in normal neonates, prepubertal children, adolescents, and adults. The values were compared with those obtained in children with premature thelarche and female sexual precocity. Unconjugated E1 and E2 fell rapidly, and the percentage of FE2 more gradually during the neonatal period and remained low prepubertally. During adolescence girls had greater increases in E1 and E2 while the percentage of FE2 was higher in boys. In premature thelarche only the FE2 was significantly increased. In sexual precocity E1, E2, and FE2 were elevated. Reference standards are provided in Tables I and II for use in the diagnosis of conditions with under- or overproduction of estrogens during growth and development.