Healthcare provider explaining what bioidentical hormone therapy is to patient

What Is Bioidentical Hormone Therapy?

Written on December 22, 2023 by Jillian Foglesong Stabile, MD, FAAFP. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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The term bioidentical hormone therapy is somewhat confusing. The Endocrine Society has recommended defining bioidentical hormones as “compounds that have exactly the same chemical and molecular structure as hormones that are produced in the human body.”[1] This definition includes both FDA-approved treatments and compounded therapies. Many people think of bioidentical hormone therapy as the compounded bioidentical hormone therapies dispensed by specialty pharmacies. But what is bioidentical hormone therapy, and is it safe for use in menopause? The answers to these questions are more complex than meets the eye and warrant further discussion.

What Is Menopause?

Menopause is defined as the absence of menstrual periods for at least a year without another explanation such as pregnancy.[2] Menopause is more common in women and people AFAB (assigned female at birth) in their 40s and 50s. Menopause can cause irregular periods, vaginal dryness, hot flashes, chills, night sweats, difficulty sleeping, mood changes, and changes in the metabolism. Dry skin and hair, as well as changes in the breast tissue, can also occur. The symptoms of menopause are the result of hormone changes in the body. The estrogen and progesterone levels decrease, and the ratios of these hormones change.

What Hormones Are Usually Used In Bioidentical Hormone Therapy?

The most common forms of commercially available hormone therapy are made with either estrogen alone or estrogen in combination with progesterone. Compounded hormone therapy may contain estrogen, progesterone, and/or testosterone in varying combinations.

Most of the hormone therapies, whether they are commercially available or compounded, are derived from plant or animal-based sources and chemically transformed to mimic the hormones produced naturally in the body.[1]

What Does Estrogen Do?

Estrogen plays a part in the function of many body systems [3]:

  • Estrogen helps with the development of the tissues of the mammary glands and other tissues in the breast as well as the development of the ducts.
  • Estrogen helps with the growth and thickening of the endometrial cells, which prepare the uterus for implantation after fertilization of an egg.
  • Estrogen supports the growth of the mucosal cells in the vagina and surrounding tissues which helps the vaginal tissues be stretchier to accommodate intercourse. Estrogen also helps thin the mucus before ovulation, which allows the sperm to move into the uterus making it easier for pregnancy to occur.
  • Estrogen helps with the development of long bones and the fusion of growth plates in utero and in childhood. It also slows the cells that reabsorb bone and aids bone strength in adults.
  • Estrogen plays a role in cholesterol metabolism by increasing high-density lipoproteins, HDL (“good” cholesterol), and triglycerides, while decreasing the low-density lipoproteins, LDL (“bad” cholesterol).

Estrogen also affects brain function, blood sugar levels, muscle mass, circulation, and moisture and collagen in the skin.[4]

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What Are the Symptoms Of Low Estrogen?

The symptoms of low estrogen are dependent on the body system affected. Low estrogen can cause irregular or absent periods, vaginal dryness, increased susceptibility to urinary tract infections, decreased bone density, and breast tenderness.

What Does Progesterone Do?

Progesterone has several roles in the body, including stabilizing the uterine lining and preparing it to receive a fertilized egg during pregnancy, maintaining the uterus during pregnancy, promoting bone-forming cells, and preventing excessive uterine lining growth and the development of endometrial cancer. Women who still have their uterus should not be on estrogen-only hormone replacement therapy. Progesterone is necessary to decrease the risk of endometrial cancer. Progesterone also regulates the menstrual cycle and bleeding during menses, helps with mood, supports thyroid function, and supports lactation.[5]

What About Testosterone?

Testosterone also plays a role in the health of women and people AFAB. Testosterone may have benefits for sexual desire, cardiovascular disease, and memory, but more studies are needed to determine efficacy and safety.[6]

Is Compounded Bioidentical Hormone Therapy Safe And Effective?

If you look for information on bioidentical hormone therapy, you’ll find a lot of mixed information out there. Supporters of compounded bioidentical hormone therapy tout efficacy and an improved safety profile over the commercially available, FDA-approved therapies. Detractors are concerned about the lack of quality studies and regulatory oversight for these medications.

Several large medical organizations including the North American Menopause Society, the American College of Obstetricians and Gynecologists, and the Endocrine Society, have issued statements expressing their concerns regarding the lack of regulation and reliable dosing for compounded hormone therapy and the lack of quality studies regarding the safety and efficacy of these compounded medications.[7-9] These organizations state that with the availability of well-regulated, reliably dosed, FDA-approved medications, there is no indication for the use of compounded hormone replacement therapies.

Learn More About Your Hormones With Everlywell

If you have questions or are concerned about your hormone levels, the first step is to discuss your concerns with your healthcare provider. You can also consider at-home testing for your hormone levels. You may also consider getting a women’s health consult with one of our virtual consultants. Take control of your health with Everlywell’s variety of health services.

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  1. Files JA, Ko MG, and Pruthi S. Bioidentical hormone therapy. Mayo Clin Proc. July 2011; 86(7): 673-680.
  2. Menopause. Cleveland Clinic. Updated May 24, 2023. Accessed December 15, 2023.
  3. Delgado BJ, Lopez-Ojeda W. Estrogen. Stat Pearls. Updated June 26, 2023. Accessed December 15, 2023.
  4. Low Progesterone. Cleveland Clinic. Updated January 16, 2023. Accessed December 15, 2023.
  5. Davis SR, Wahlin-Jacobsen S. Testosterone in women—The clinical significance. Lancet Diabetes Endocrinol. 2015 Dec; 3(12):980-92.
  6. Estrogen. Clevland Clinic. Updated February 8, 2022. Accessed December 15, 2023.
  7. Pinkerton JV. The truth about bioidentical hormone therapy. The Female Patient. September 2012; 37: 16-20. Accessed December 15, 2023.
  8. Compounded Bioidentical Menopausal Hormone Therapy. American College of Obstetricians and Gynecologists. November 2023. 142(5):1266-1273.
  9. Santoro N, Braunstein GD, Butts CL, et. al. Compounded bioidentical hormones in endocrinology practice: An endocrine society scientific statement. J Clin Endocrinol Metab. April 2016; 101(4): 1318-1343.
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