Estradiol is a vital hormone that plays a key role in reproductive health and overall well-being. It’s the most potent form of estrogen during the reproductive years and is essential for maintaining hormonal balance, supporting bone health, and regulating various bodily functions.
This article examines the functions of estradiol, its forms in hormone replacement therapy (HRT), potential side effects, and commonly asked questions, offering a comprehensive overview of this important hormone.
“While estrogen is the primary hormone that women need when going through the menopause transition, Winona’s doctors always additionally prescribe progesterone for those who still have a uterus. This ensures the health of the uterine lining and prevents uterine cancer.”
What is estradiol?
The following are the four main types of estrogen:(1)
Estrone (E1): This is a weaker form of estrogen that the body can convert into other types when needed.
Estradiol (E2): Estradiol is the dominant estrogen during reproductive years, supporting fertility, bone health, and overall hormonal balance.
Estriol (E3): This is the weakest form of estrogen and is most prominent during pregnancy, as it’s produced in large amounts by the placenta.
Estetrol (E4): This form of estrogen is produced exclusively during pregnancy and plays a role in fetal development.
Estradiol is the strongest and most abundant form of estrogen in the body, making it essential for regulating reproductive health, maintaining bone density, and supporting overall well-being.
What does estradiol do?
Estradiol plays a critical role in the body, particularly in the female reproductive system. It’s responsible for developing female sexual characteristics and regulating various processes essential for overall health.(1)
It moves through the body in two forms: free (unattached) or attached to proteins like sex hormone-binding globulin (SHBG) or albumin. The free estradiol can enter cells directly and connect to estrogen receptors inside the cell.
Once bound, this hormone-receptor pair travels into the cell's nucleus and interacts with specific parts of the DNA. This interaction activates certain genes that trigger responses in the body, such as regulating reproductive functions, bone health, and other processes.
Estradiol levels are carefully regulated by a feedback system involving the brain's hypothalamus and pituitary gland, which helps maintain hormonal balance. This system ensures that the body produces the right amount of estradiol to support its various functions.(1)
Some of the functions of estradiol on various parts of the body include the following:(1)
Breasts: Estradiol supports the development of mammary glands and ducts during puberty and pregnancy.
Uterus: It promotes the growth and thickening of the endometrial lining during the menstrual cycle, preparing the uterus for pregnancy.
Vagina: It encourages the growth of epithelial cells in the vaginal and vulvar mucosa to support tissue health and moisture.
Bones: Estradiol stimulates the growth of long bones and the fusion of growth plates during puberty. It also protects against bone loss by inhibiting osteoclast activity and helps prevent osteoporosis.
Cardiovascular System: It improves lipid profiles by increasing HDL (good cholesterol) and decreasing LDL (bad cholesterol), reducing the risk of coronary artery disease when used early in postmenopausal women.
Estradiol Levels in Women
Estradiol levels naturally fluctuate throughout a woman’s life, especially during the menstrual cycle, perimenopause, and menopause. During menopause, levels typically drop below 50 pg/ml. In contrast, levels between 50 pg/ml and 400 pg/ml are considered normal during perimenopause or a regular menstrual cycle.(2)
However, hormone tests can be inaccurate, as hormone levels change daily and even throughout the day. Therefore, measuring estradiol levels can’t accurately pinpoint a phase, indicate a deficiency, or determine whether HRT is necessary. Symptoms are often a better guide for deciding the dose or effectiveness of HRT for patients. This is why many physicians suggest keeping a symptom diary, as it can reveal patterns and provide a more complete understanding of hormonal changes over time.
Forms of Estradiol in HRT
Estradiol is available in various forms to suit individual needs and preferences.(1)
Estradiol Patch: This transdermal option delivers estrogen through the skin directly into the bloodstream. The patch provides a steady release of estradiol and needs replacement every four days or per the physician's instructions. For women with an intact uterus, progesterone should be taken in addition to the patch to maintain a healthy endometrial lining.
Estradiol Tablets: This oral form of hormone therapy provides estrogen to the body through the digestive system. These tablets are usually taken once daily, at the same time each day, to maintain stable hormone levels. Similar to the patches, progesterone tablets are recommended along with estrogen tablets to prevent the risk of endometrial hyperplasia in women with a uterus.
Estradiol Body Cream: Body creams allow estrogen to be absorbed into the bloodstream through the skin. The frequency of use varies depending on the prescribed dose but is often applied daily. Body cream is an easy-to-use option for those who prefer not to take oral medications. An estradiol body cream with progesterone is a recommended option for women with a uterus.
Estradiol Vaginal Cream: Localized vaginal cream is applied directly inside the vagina and helps manage urogenital symptoms like vaginal dryness, itching, and discomfort caused by low estrogen levels. Initially, vaginal cream is used daily for one to two weeks, and then the frequency is reduced to one to three times per week for maintenance, depending on the physician's recommendation.
Potential Side Effects of Estradiol
While estradiol is generally well-tolerated, it can cause side effects in some individuals. These effects can vary from person to person, and not everyone experiences them. It’s important to be aware of the potential side effects and discuss any concerns with a healthcare provider.(1)
Breast tenderness
Nausea and vomiting
Bloating and stomach cramps
Headaches
Hyperpigmentation of the skin
Hair loss
Vaginal itching
Breakthrough uterine bleeding
