PERCENTAGE OF DIALYZABLE ESTRADIOL-17β (DE₂) FROM BIRTH TO ADULTHOOD AND IN SEXUAL PRECOCITY AND PREMATURE THELARCHE

Abstract

We used equilibrium dialysis to determine % of radio-labeled E₂ unbound to sex hormone binding globulin (SHBG). See Table. DE₂ in cord blood was 6 x that of mothers. Therefore (unlike the mother), SHBG (or other circulating binding protein) affords the fetus little protection against high E₂ levels. A tissue E₂ binding protein could be protective. The lowest DE₂ was in prepubertal children protecting them from secondary effects of circulating E₂ (< 10 pg/ml). In sexual precocity and premature thelarche, DE₂ was similar to adult females; since some cases of thelarche do not have elevated serum E₂, the breast development could be 2 to increased DE₂. Estrogen induced increases in SHBG from adult males → females → pregnant females are responsible for the decrease in % DE₂ between those groups.

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