How Does Estradiol Work in the Body?

The human body is complex and can make different types of hormones to help it function appropriately. One such hormone is estradiol. Estradiol is a major hormone in women's health and fertility. [1] Continue reading to learn more about what estradiol is, its role in women's menstrual health, if you may have a hormone imbalance, and more.

What Is Estradiol?

Estradiol is a type of sex hormone known as estrogen. [1] It is the most active form of estrogen, which is the human female sex hormone. So, how does estradiol work? It is an essential hormone that regulates a wide range of processes in the body. During the reproductive years, the role of estradiol in women is to regulate and maintain reproductive organs such as the vagina and fallopian tubes. [1] The fallopian tubes are where the eggs travel from the ovaries to the uterus.

Estradiol is produced primarily in the ovaries. It can also be made by the placenta during pregnancy and in the adrenal glands (a gland that produces various hormones in the body). [2] As a woman ages, the normal level of estradiol changes and can affect a woman's health and quality of life. Estradiol plays an important role during a woman's menstrual cycle, regulating egg release and supporting fertility. [1,2]

Estradiol's role in the body extends far beyond reproduction. [3] Not only does estradiol regulate a woman's menstrual cycle, but it also can affect bone, cardiovascular, and behavioral health. [4]

The Role of Estradiol in Menstrual Health

During the menstrual cycle, the uterus experiences fluctuations in two sex hormones, estradiol and progesterone, every month. These two hormones are essential for regulating the growth and variation of the endometrium, which is the inner lining of the uterus. [3] These changes in estradiol and progesterone levels help to regulate the menstrual cycle and can also support a pregnancy.

The menstrual cycle consists of three phases: follicular (before ovulation), ovulatory (during egg release or ovulation), and luteal (after ovulation). [3]

• Follicular: The follicular phase is characterized by a gradual increase of estradiol as the egg starts to develop. The endometrium begins to thicken in preparation for possible implantation of a fertilized egg.
• Ovulatory: Following the follicular phase is the ovulatory phase, where estradiol reaches its highest level before ovulation (egg release). Estradiol functions during this phase to stimulate the release of a mature egg.
• Luteal: During the final luteal phase, a drop in estradiol level followed by high progesterone production prepares the uterus for potential fertilization and implantation.

Regulating normal fluctuations of estradiol levels is essential for normal endometrium development and menstrual health. An imbalance in estradiol levels can disrupt the normal hormonal cycle regulating egg development and ovulation. [5] Estradiol imbalance can result in irregular or missed menstrual cycles, which reduces the chance of conception. [2] If estradiol levels are too low, then ovulation may not occur.

Low estradiol levels are associated with premenopausal, irregular menstrual cycles and can contribute to symptoms such as hot flashes, mood swings, and vaginal dryness. [5,6] Conversely, excessively high estradiol levels can often be seen in conditions like polycystic ovary syndrome (PCOS), preventing the proper timing of ovulation or causing irregular cycles. [7] When estradiol levels are high, this can lead to increased weight gain and prolonged and heavier bleeding. [5,7] For these reasons, estradiol imbalance can impact a woman's fertility and overall health.

Other Effects of Estradiol on The Body

Not only does estradiol help maintain a healthy menstrual cycle, it also plays a critical role in maintaining bone health by directly regulating the bone cells that build new bones. [4] This process ensures that bones remain dense and strong. However, as women approach menopause, estradiol levels naturally decline, leading to a reduction in bone cell activity. [4,8] This occurs because the bone is broken down faster than it can be rebuilt, resulting in bone loss and weakening. Gradually, this leads to osteoporosis, a condition where the bones become weak and brittle. Some ways to consider addressing estradiol decline are through lifestyle changes, dietary adjustments, or hormone therapy, which can help mitigate the risk of osteoporosis and preserve bone health in postmenopausal women. [9]

Estradiol also helps regulate brain function, which in turn influences mood. Because estradiol works differently in various parts of the brain, it can significantly impact behavioral health. [10,11] When the normal estradiol level balance is disrupted, it can lead to increased mood swings and behavioral changes. [10,11] This wide-ranging influence means that disruption in normal estradiol levels can have a cascading effect on behavioral health. Women with premenstrual dysphoric disorder (PMDD) may experience severe emotional symptoms, such as irritability, sadness, and fatigue, alongside physical symptoms like bloating and breast tenderness. [12] These symptoms often interfere with daily life and relationships, making PMDD a debilitating condition for many women.

Estradiol can also affect cardiovascular or heart health by altering cell functions in the heart. [13] Estrogen influences cell functions by affecting how the heart contracts and pumps blood. Estrogen's ability to influence cell functions is crucial because it can affect the risk of irregular heartbeat and protect the heart from deposits of fatty material on the inner walls of blood vessels. [13,14] Maintaining normal estradiol levels can have a significant positive effect on cardiovascular health.

Measuring and Monitoring Estradiol

Estradiol is an essential hormone that regulates the menstrual cycle. If you're experiencing missed or erratic periods, a blood test for estradiol can help identify hormonal imbalances. Healthcare providers often check estradiol levels in women to inform them of potential risks, such as pregnancy, infertility, or menopause. [15,16] Estradiol levels are typically measured through a simple blood draw. In premenopausal women, estradiol levels can range between 30–400 pg/mL. [16] Postmenopausal women generally have lower levels, often below 30 pg/mL. [16] However, normal estradiol ranges can vary by age, sex, and menstrual cycle phases.

Regular monitoring of estradiol helps healthcare providers spot hormone imbalances early. Monitoring estradiol over time rather than relying on a single test can help reveal patterns and trends that can guide treatment decisions. For women who have difficulty conceiving, estradiol testing is usually part of a more extensive fertility workup to determine if ovulation is happening normally. [16] If you are undergoing fertility treatments, estradiol measurements can indicate how well the ovaries are responding to medication. [18]

Various conditions can alter estradiol production. [19] Checking estradiol levels can help pinpoint underlying health conditions earlier, and a treatment plan can be started. In menopause management, tracking estradiol levels alongside symptoms can help your healthcare provider adjust therapy appropriately. [15,16] Keeping track of estradiol levels can ensure that any hormonal imbalances are caught early, reducing potential complications down the road.

Key Summary

Estradiol is a sex hormone that plays a critical role in regulating menstrual cycles, fertility, and various other functions in the body, including bone health, brain function, and cardiovascular health. Maintaining normal levels of estradiol ensures the proper development and maintenance of reproductive organs, while its variations drive the phases of the menstrual cycle. Beyond reproductive health, estradiol helps maintain strong bones, regulate moods, and protect cardiovascular health by influencing heart function and reducing the risk of conditions like atherosclerosis.

Imbalances in estradiol can disrupt these vital processes, leading to issues such as irregular periods, infertility, osteoporosis, mood disorders, or cardiovascular problems. Monitoring estradiol levels is an essential step in identifying hormonal imbalances and managing health concerns early. Whether addressing fertility challenges, menopausal symptoms, or underlying conditions like PCOS, tracking estradiol over time enables healthcare providers to monitor treatment and interventions effectively.

At-Home Lab Testing and Telehealth With Everlywell

By understanding and maintaining healthy estradiol levels, individuals can optimize their overall health and prevent potential complications associated with hormonal imbalances. At Everlywell, you can measure your estradiol levels at home with our at-home Women’s Health Test or our at-home Women’s Fertility Test. If you are concerned about hormone imbalances, you can schedule a virtual visit with one of our certified healthcare providers.

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