What is estrogen therapy?

Updated: Oct 16, 2018
  • Author: Janice L Bacon, MD; Chief Editor: Richard Scott Lucidi, MD, FACOG  more...
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Answer

Answer

Estrogen therapy, with or without a progestogen (progesterone and progestin), has long been prescribed to treat menopausal symptoms. It has been extensively studied, and it is the most consistently effective therapy for vasomotor symptoms. [1] Data from numerous studies suggest that oral, transdermal, or vaginal hormone therapy reduces the severity of hot flashes by 65-90%. [2, 3, 4, 5, 6, 7, 8, 9, 10]  

Estrogen, a steroid hormone, is derived from the androgenic precursors androstenedione and testosterone by means of aromatization. In order of potency, naturally occurring estrogens are 17 (beta)-estradiol (E2), estrone (E1), and estriol (E3). The synthesis and actions of these estrogens are complex.

In brief, these forms of estrogen can be summarized as follows:

  • Estradiol - Primarily produced by theca and granulosa cells of the ovary; it is the predominant form of estrogen found in premenopausal women

  • Estrone - Formed from estradiol in a reversible reaction; this is the predominant form of circulating estrogen after menopause; estrone is also a product of the peripheral conversion of androstenedione secreted by the adrenal cortex

  • Estriol - The estrogen the placenta secretes during pregnancy; in addition, it is the peripheral metabolite of estradiol and estrone; it is not secreted by the ovary [11]

Table 1 summarizes normal concentrations of the various estrogens.

Table 1. Production and Concentrations of Estrogens in Healthy Women [11] (Open Table in a new window)

Phase

17b-Estradiol

Estrone

Estriol

Serum

Concentration, pg/mL

Daily Production,

mg

Serum

Concentration, pg/mL

Daily

Production, mg

Serum

Concentration, pg/mL

Daily Production,

mg

Follicular

40-200

60-150

30-100

50-100

3-11

6-23

Preovulatory

250-500

200-400

50-200

200-350

-

-

Luteal

100-150

150-300

50-115

120-250

6-16

12-30

Premenstrual

40-50

50-70

15-40

30-60

-

-

Postmenstrual

< 20

5-25

15-80

30-80

3-11

5-22

Estrogens affect many different systems, organs, and tissues, including the liver, bone, skin, gastrointestinal (GI) tract, breast, uterus, vasculature, and central nervous system (CNS). These effects appear to become most prominent during times of estrogen deficiency, such as the menopausal transition.


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