title: Bioavailability of natural estrogens in young females with secondary amenorrhea.
abstract: The bioavailability of 17 beta-estradiol valerate, free 17 beta-estradiol and Premarin was studied in 24 subjects suffering from secondary amenorrhea. 17 beta-estradiol and estrone were determined by specific radioimmunoassay systems. All estrogens were administered as single oral doses. The amounts applied were 2 and 10 mg of 17 beta-estradiol valerate or equivalent amounts of the free estradiol and Premarin, respectively. No elevations of 17 beta-estradiol serum levels were recorded at the lower dosages, whereas the increases of estrone serum levels were approximately tenfold over basal levels. Similar data were recorded in a group of 3 women with normal cycles after the ingestion of 2 mg of 17 beta-estradiol valerate. All subjects responded to the higher doses of estrogens with a moderate increase of 17 beta-estradiol serum levels, but with much higher elevation of estrone levels. These data suggest a rapid conversion of 17 beta-estradiol into estrone. The biological activity of 2 mg 17 beta-estradiol valerate is discussed on grounds of a possible metabolism of estrone sulfate at the target tissues.
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000568:Amenorrhea / Q000378:metabolism*; D001682:Biological Availability; D004958:Estradiol / Q000008:administration & dosage / Q000097:blood; D004967:Estrogens / Q000008:administration & dosage / Q000378:metabolism*; D004966:Estrogens, Conjugated (USP) / Q000008:administration & dosage / Q000097:blood; D004970:Estrone / Q000097:blood; D005260:Female; D006801:Humans
chemical_list: D004967:Estrogens; D004966:Estrogens, Conjugated (USP); D004970:Estrone; D004958:Estradiol