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Estrogen: Types, Functions & Levels

Gynecologist explaining menstrual cycle

Estrogen is a hormone that performs various functions in the body. In females, estrogen contributes to the development and maintenance of female characteristics such as breasts and pubic hair. Estrogen is produced by the ovaries, adrenal glands, and fatty tissues. Both sexes create estrogen, but women create more of it.

Estrogen plays a critical role in cognitive health, bone health, cardiovascular function, and other essential bodily processes. However, estrogen is most well known for its function in female reproductive and sexual wellness, along with progesterone.

In this article, we will examine estrogen including how it works, what happens when levels fluctuate, and its medicinal purposes.

Types of Estrogen

There are three major different types of estrogen including:

Estrone (E1)

Estrone is a weaker form of estrogen that presents itself in the body post-menopause. The body can convert estrone into other forms of estrogen, as needed. 

Estradiol (E2)

Both sexes produce estradiol, which is the most common type of estrogen produced during a woman’s reproductive years. Estradiol is the variety that most people think of when they think of estrogen. 

However, too much of this hormone can result in acne, low sex drive, osteoporosis, and depression. Dangerously elevated levels of estradiol can increase a patient’s risk of uterine as well as breast cancer. On the other hand, dangerously low levels of estradiol can cause weight gain as well as cardiovascular disease.

Estriol (E3)

During pregnancy, estriol levels rise in order to help the uterus grow and the body to prepare for childbirth. Estriol levels are at their highest just prior to birth.


Estrogen empowers the following organs to operate:

Ovaries: Estrogen helps stimulate the development of the ovum (egg) follicle.

Vagina: Estrogen sustains the thickness of the vaginal wall and fosters lubrication.

Uterus: Estrogen strengthens and supports the uterine lining. Additionally, this hormone controls the thickness and flow of uterine mucus secretions.

Breasts: The body harnesses estrogen to create breast tissue and halt the flow of milk after weaning.

Estrogen Levels

Estrogen levels fluctuate during the menstrual cycle, over a female’s lifetime, and from person to person. These variations can occasionally generate symptoms such as changes in mood prior to menstruation and hot flashes during menopause.

Factors that can influence estrogen levels include:

● aging

● puberty

● diabetes


● strenuous exercise

● high blood pressure

● BMI (too high or low)

● primary ovarian insufficiency

● an underactive pituitary gland

● polycystic ovary syndrome (PCOS)

● tumors in the ovaries or adrenal glands

● some congenital diseases (like Turner’s syndrome)

● pregnancy, when the body is preparing for childbirth, and breastfeeding

● medications (including ampicillin, hormones, drugs with estrogen, tetracyclines, and phenothiazines)

Come back next week for part two where we will be discussing estrogen imbalances, sources, and uses.

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