Estrogen Replacement Therapy

Estrogen Types and Estrogen Replacement Therapy

Estrogen replacement therapy is most often prescribed to treat symptoms of menopause that result from hormone imbalance. An imbalance in hormones can result in symptoms like hot flashes and night sweats, mood changes, decreased libido, and vaginal atrophy and dryness. Health complications, like decreased bone density that can lead to osteoporosis, are also associated with lower levels of estrogen. With hormone replacement therapy, levels of estrogen are increased and balanced with other hormones to reduce symptoms of menopause.

What is Estrogen?

Estrogen hormones play an important role in a woman’s reproductive system and overall health. They are responsible for secondary sex characteristics and affect metabolism, sex drive, vaginal health and many other parts of a woman’s body. Estrogen hormones are synthesized in a chain of hormonal reactions by the ovaries and also by the adrenal glands.

What Are the Types of Estrogen?

There are three major estrogens that are produced in women, which are estrone (E1), estradiol (E2), and estriol (E3). For women who are in their reproductive years, estradiol is the most active type of estrogen and has the highest levels. The predominant hormones change during pregnancy when estriol levels are higher and during menopause when estrone is the only estrogen that continues to be produced.

Estrone (E1)

Estrone is found in increased amounts in postmenopausal women. Because of that and its connection to an increased risk of cancer it is not included as part of estrogen replacement therapy. Taking estradiol orally can lead to increased levels of estrone as it is metabolized by the liver. Increased levels of estrone in the body are avoided by the use of non-oral methods of estradiol delivery like creams and gels.

Estradiol (E2)

The most commonly prescribed type of estrogen for HRT is estradiol. It is the most potent type of estrogen and the one that is predominant in women during their reproductive years. Replacing estradiol mimics the release of this essential female hormone from the ovaries. Estradiol has the potential to reduce multiple symptoms of menopause including hot flashes, night sweats, and vaginal symptoms. It has also been shown to reduce the risk of osteoporosis and coronary artery disease.

Estriol (E3)

Estriol is sometimes considered a “weaker” estrogen but can be an effective part of HRT, especially when applied locally to treat vaginal symptoms of menopause. Although estriol has been used in Europe for over 60 years, it has failed to gain widespread use in the United States mostly due to the fact that it cannot be patented.

Hormone replacement therapy uses estrogen and progesterone supplements to restore hormone balance. The appropriate dosages are determined both by observation of symptom relief and through using hormone testing. The test results will be compared to standard levels and used to determine initial dosages for hormone replacement. Levels need to be monitored continuously throughout the therapy to maintain a balance of hormones that is appropriate for the individual woman.

Esterified Estrogen vs. Conjugated Estrogen

The brand name product Premarin is a conjugated estrogen derived from mare’s urine that is a mix of several different estrogens, some of which are not found naturally in the body. Esterified estrogens are synthesized from plant sources like wild yams that contain only estrogens that behave like naturally produced hormones in the body. Esterified estrogens are what are used as a part of what is sometimes referred to as “bioidentical” hormone replacement therapy. There is some confusion about the term, but it really just refers to a protocol that involves not using conjugated equine estrogens, optimizing delivery methods, and customizing dosages to an individual’s hormonal makeup.