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What is Estradiol?

Updated

Estradiol (E2), also known as 17β-estradiol, is a steroid hormone and the primary form of estrogen in humans. It plays a crucial role in regulating reproductive and sexual functions in both females and males. In premenopausal women, estradiol is the most potent estrogen produced by the ovaries and is vital for maintaining fertility and secondary sexual characteristics. Estradiol binds to specific nuclear receptors in various tissues, including the reproductive tract, breast, pituitary, hypothalamus, liver, and bone, thereby activating the transcription of genes involved in reproductive and secondary sexual characteristics. Its functions extend beyond the reproductive system, influencing bone density, cardiovascular health, cognitive function, and skin health by promoting collagen production and maintaining skin thickness and moisture.

In men, estradiol is produced from testosterone through a process called aromatization, where the enzyme aromatase converts testosterone to estradiol. Estradiol in men plays a role in maintaining bone density, modulating libido and erectile function, and contributing to cardiovascular health by affecting lipid metabolism and vascular function. When testosterone levels are low, there is less substrate for aromatase to convert into estradiol, leading to lower estradiol levels. This imbalance can contribute to symptoms associated with low testosterone, such as decreased libido, erectile dysfunction, reduced bone density, and mood disturbances. Hormone Replacement Therapy (HRT) can help normalize both testosterone and estradiol levels in men, but it is crucial to monitor estradiol levels to avoid potential complications like gynecomastia and cardiovascular issues. Elevated estradiol levels are a risk factor for certain cancers, including breast cancer, and can have environmental impacts, affecting aquatic life and potentially entering the human water supply. 

Further Reading:

  1. Pescatori, S., Berardinelli, F., Albanesi, J., Ascenzi, P., Marino, M., Antoccia, A., Alessandra di Masi, & Filippo Acconcia. (2021). A Tale of Ice and Fire: The Dual Role for 17β-Estradiol in Balancing DNA Damage and Genome Integrity. Cancers, 13(7), 1583–1583. https://doi.org/10.3390/cancers13071583
  2. Estradiol Vaginal Ring. (2020). Definitions. https://doi.org/10.32388/6x8uj3
  3. Lee, Y.-S., Feng, C.-W., Peng, M.-Y., Chan, T.-F., & Chen, Y.-C. (2021). Neuroprotective Effects of Estradiol plus Lithium Chloride via Anti-Apoptosis and Neurogenesis Pathway in In Vitro and In Vivo Parkinson’s Disease Models. Parkinson’s Disease, 2021, 1–15. https://doi.org/10.1155/2021/3064892
  4. Chimchirian, R. F., Suri, R. P. S., & Fu, H. (2007). Free Synthetic and Natural Estrogen Hormones in Influent and Effluent of Three Municipal Wastewater Treatment Plants. Water Environment Research, 79(9), 969–974. https://doi.org/10.2175/106143007x175843
  5. Therapeutic Estradiol. (2020). Definitions. https://doi.org/10.32388/94lu85
  6. Estradiol Hemihydrate. (2020). Definitions. https://doi.org/10.32388/lr1h7d
  7. Geraci, A., Calvani, R., Ferri, E., Marzetti, E., Arosio, B., & Cesari, M. (2021). Sarcopenia and Menopause: The Role of Estradiol. Frontiers in Endocrinology, 12. https://doi.org/10.3389/fendo.2021.682012
  8. Schmitz, D., Ek, W. E., Berggren, E., Höglund, J., Karlsson, T., & Johansson, Å. (2021). Genome-wide Association Study of Estradiol Levels and the Causal Effect of Estradiol on Bone Mineral Density. The Journal of Clinical Endocrinology & Metabolism, 106(11), e4471–e4486. https://doi.org/10.1210/clinem/dgab507
  9. Ramasamy, R., Schulster, M., & Bernie, A. (2016). The role of estradiol in male reproductive function. Asian Journal of Andrology, 18(3), 435. https://doi.org/10.4103/1008-682x.173932
  10. Cooke, P. S., Nanjappa, M. K., Ko, C., Prins, G. S., & Hess, R. A. (2017). Estrogens in Male Physiology. Physiological Reviews, 97(3), 995–1043. https://doi.org/10.1152/physrev.00018.2016