title: Serum and tissue hormone levels of vaginally and orally administered estradiol.
abstract: OBJECTIVE
  Our purpose was to determine serum and endometrial estradiol levels when micronized estradiol is administered vaginally and orally.
  
  
  METHODS
  Five subjects were given oral estradiol (2 mg twice daily), during an artificial luteal phase, and another group of 5 subjects were given the same dose of estradiol by the vaginal route. Endometrial biopsies and blood samples were obtained on day 21 of the cycle, 2 hours after the last dose was administered. Tissue and blood samples were assayed for estradiol.
  
  
  RESULTS
  Serum estradiol levels were significantly higher with vaginally administered estradiol than with orally administered estradiol (2344 +/- 398 vs 279 +/- 76 pg/mL, P <.005). Endometrial estradiol concentrations were also significantly higher with vaginally administered estradiol than with the oral preparation (918 +/- 412 vs 13 +/- 2 pg/mg protein, P <.05).
  
  
  CONCLUSIONS
  Vaginal administration of estradiol is more effective in increasing serum and endometrial levels of estradiol than the oral route and may represent the optimal route of administration for recipients of egg donation. If the vaginal route of estradiol administration is considered for menopausal replacement therapy, much lower doses of the standard oral quantities should be used. Furthermore, if the uterus is present, a progestin must be used to compensate for the high tissue levels of estradiol.
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Southern California School of Medicine, Los Angeles, USA.
authors.forename: D E
authors.initials: DE
authors.lastname: Tourgeman
authors.forename: E
authors.initials: E
authors.lastname: Gentzchein
authors.forename: F Z
authors.initials: FZ
authors.lastname: Stanczyk
authors.forename: R J
authors.initials: RJ
authors.lastname: Paulson
mesh_terms: D000282:Administration, Intravaginal; D000284:Administration, Oral; D000328:Adult; D004624:Embryo Transfer; D004717:Endometrium / Q000378:metabolism*; D004958:Estradiol / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D007700:Kinetics; D008875:Middle Aged; D011374:Progesterone / Q000008:administration & dosage
chemical_list: D011374:Progesterone; D004958:Estradiol