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Hormone Balance

  • The intravaginal administration of estriol prevents recurrent urinary tract infections in postmenopausal women, by modifying the vaginal flora and significantly lowering vaginal pH. Lactobacilli (absent prior to therapy) reappeared after one month in 61% of patients given estriol but in no patient receiving placebo. (Cardozo et al, 1998: Raz & Stamm, NEJM 1993; 329:753-6).
  • It is suggested that Vitamin E administered daily with estriol therapy will improve Estriol's activity in the body. Oral doses of up to 16mg per day have been documented. In clinical practice, we typically see doses ranging between 0.5-2mg. Hybrid combinations using estriol as their main component have become very popular in estrogen replacement therapy. Biest (using 2 estrogens, generally Estriol and Estradiol) is a compounded combination of Estriol and Estradiol, estriol usually being the major component. The theory is to use an estrogen complex, which has the protective effects of estriol on the breast and uterus while recognizing the benefits of estradiol and estrone for bones and cardiac protection. Also it is generally recognized that 2 or more drugs with the same pharmacologic action in the body when used together can elicit a greater response by acting synergistically. This synergism, therefore, allows a reduction of each single component while producing the same therapeutic effect. This generally results in fewer side effects and a better overall therapeutic response.
  • A Taiwan study concluded that estriol was very effective in the improvement of major subjective climacteric complaints in 86% of patients, especially hot flush and insomnia within 3 months. The atrophic genital changes caused by estrogen deficiency were also improved satisfactorily.
  • Oral Estriol has been widely used in Europe for decades (over 60 years)-typical dosing is 0.5mg (topically) every other day.
  • Estriol skin cream and oral Estriol has been used in North America for at least 15 years.
  • Oral Estriol has been studied extensively worldwide and especially in Japan. (New papers are presented every month).
  • Estriol may offer many benefits for post-menopausal women…without the side effects. Estriol can be given orally with more confidence because there are no “downstream” metabolites.
  • The primary forms of estrogen include three substances- estrone, estradiol and estriol. Estrone sulphate is the form of estrogen found in Premarin®, while 17-B Estradiol is the form of estrogen found in the products Estrace®, Vivelle®, Climara®, as well as compounded form called Biest.
  • Although estradiol and estrone are bio-identical in that they match our own bodies they are the more aggressive estrogens and long-term use significantly increases the risk of breast and ovarian cancer when taken for more than 10 years.
  • During pregnancy, Estriol is produced in much greater quantities than Estrone and Estradiol-hence its protective effect. (We all swam in it)
  • Estriol has a much less stimulating effect on the breast and uterine lining than estradiol and estrone. Estradiol is 1000 times more stimulating to the breast tissue than is estriol.
  • In 1966, H.M.Lemon, M.D. demonstrated that women with breast cancer have lower estriol levels. Later he showed that women without breast cancer had naturally higher estriol levels (compared to estrone and estradiol) than those with breast cancer.
  • Receptor binding studies have indicated that estriol has only low relative binding affinity to endometrial estrogen receptors (about 10% of Estradiol), whereas it has a relatively strong binding affinity to vaginal estrogen receptors (equal to Estradiol). This means that after a single dose of estriol, the binding to the endometrial estrogen receptor is too short to induce true proliferation, while its binding to the vaginal estrogen receptor is sufficient to exert a full vaginotropic effect. Because of estriol's strong vaginotropic effect it is thought to be the estrogen most beneficial to the vagina, cervix, and vulva. In cases of postmenopausal vaginal dryness and atrophy, which predisposes a woman to vaginitis and cystitis, estriol supplementation would theoretically be the most effective (and safest) estrogen to use.


Effects of protracted administration of estriol on the lower genito urinary tract in postmenopausal women. - Iosif CS - Arch Gynecol Obstet - 01-JAN-1992; 251(3): 115-20 (From NIH/NLM MEDLINE): 80 postmenopausal women with symptoms of vaginal atrophy and urinary incontinence, 8-10 years of treatment, 75% of the women reported significant subjective improvement of stress incontinence, and the risk of estriol treatment is insignificant.

Schar G, et al, Effect of vaginal estrogen therapy on urinary incontinence in postmenopause. Zentralbl Gynakol 1995; 117:77-80 (article in German) 135 women, 3.5 mg estriol intravaginally x 3 months, 63% reported significant improvement in incontinence

John R. Lee, M.D. with Virginia Hopkins. What your Doctor may not tell you about menopause. The breakthrough book on natural progesterone. Warner Books, Inc. 1996

Tzay-Shing Yang M.D. et al., Efficacy and safety of estriol replacement therapy for climacteric women. Chin Med J (Taipei) 1995;55:386-91

A. H. Follingstad M.D. Estriol, the forgotten estrogen. JAMA, Jan. 2 1978 Vol 239 No.1.

Hiroshi Minaguchi M.D. et al, Yokohama City University, School of Medicine, Yokohama, Japan. J. Obstet. Gynaecol. Res. Vol 22, No. 3: 259-265 1996.

Raul Raz, M.D., Walter E. Stamm, M.D. A controlled trial of intravaginal estriol in postmenopausal women with recurrent urinary tract infections. N. England J. Med. 1993;329:753-6.

G. P. Vooijs, T. B. P. Geurts, Review of the endometrial safety during intravaginal treatment with estriol. European Journal of Obstet. and Gynec. and Reprod. Biology 62 (1995) 101-106.

Dessole S. et al. Menopause. 2004; 11:49-56

Menopause. 2004; Jan-Feb;11(1):49-56. Efficacy of low-dose intravaginal estriol on urogenital aging in postmenopausal women. Dessole S, Rubattu G, Gallo O, Capobianco G, Cherchi PL, Marci R, Cosmi E. Locate on PubMed with PMID: 14716182

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