Estradiol Explained: The Truth About Oral Estrogen, Estrone, Testosterone & Informed Consent

In this episode, Dr. Brendan McCarthy breaks down one of the most misunderstood topics in hormone replacement therapy: estradiol. Not all estrogen is the same—and how estradiol is delivered can dramatically affect hormone balance, inflammation, clotting risk, testosterone levels, and overall health outcomes. Dr. McCarthy discusses: • Why route of administration matters (oral, patch, injectable, topical, vaginal, pellet) • How oral estradiol converts to estrone • The differences between estradiol (E2), estrone (E1), and estriol (E3) • Estrone's relationship to inflammation and metabolic health • Oral estrogen and clotting risk • Oral estrogen's effect on SHBG and free testosterone • The impact of oral estrogen on IGF-1 and growth hormone signaling • Why informed consent should be central to hormone therapy • Benefits and limitations of pellets, patches, creams, and injections • Estriol and emerging research in autoimmune conditions such as multiple sclerosis At Protea Medical Center, our philosophy is simple: patients deserve complete information so they can make empowered decisions about their health. 📍 Protea Medical Center Tempe, Arizona 👍 If you found this episode helpful, please like, subscribe, and share it with someone who may benefit. ⚠️ This podcast is for educational purposes only and does not constitute medical advice. Always consult your healthcare provider before making changes to your treatment plan. REFERENCES (Abbreviated) • Kuhl H. Climacteric. 2005. • O'Connell MB. J Clin Pharmacol. 1995. • Canonico M et al. Circulation. 2007. • Vinogradova Y et al. BMJ. 2019. • Weissberger AJ et al. JCEM. 1991. • Bellantoni MF et al. JCEM. 1996. • Kam GY et al. JCEM. 2000. • Brown KA et al. JCEM. 2017. • Iyengar NM et al. npj Breast Cancer. 2021. • Bowers LW et al. Breast Cancer Res Treat. 2015. • Lee AA & Den Hartigh LJ. Front Endocrinol. 2025. • Kern PA et al. Am J Physiol Endocrinol Metab. 2001. • Bastard JP et al. JCEM. 2002. • Qureshi R et al. Cell Metab. 2020. • Cushman M et al. Circulation. 1999. • Key TJ et al. J Natl Cancer Inst. 2002. • Sicotte NL et al. Ann Neurol. 2002. • Voskuhl RR et al. Lancet Neurol. 2016. • Soldan SS et al. J Immunol. 2003. • Taylor MB & Gutierrez MJ. Pharmacotherapy. 2008. • FDA Drug Safety Communication. 2010. • Greenblatt RB & Suran RR. Am J Obstet Gynecol. 1949.   Dr. Brendan McCarthy is the founder and Chief Medical Officer of Protea Medical Center in Arizona. With over two decades of experience, he’s helped thousands of patients navigate hormonal imbalances using bioidentical HRT, nutrition, and root-cause medicine. He’s also taught and mentored other physicians on integrative approaches to hormone therapy, weight loss, fertility, and more. If you’re ready to take your health seriously, this podcast is a great place to start. 👇 Tap Subscribe to learn more about what’s actually happening in your body, and what to do about it. 📘 Read Dr. McCarthy’s Book: Jump Off the Mood Swing – A Sane Woman’s Guide to Her Crazy Hormones https://www.amazon.com/Jump-Off-Mood-... 📲 Follow Dr. McCarthy: Instagram: @drbrendanmccarthy TikTok: @drbrendanmccarthy Website: www.protealife.com 💬 Got a question or topic for a future episode? Let us know in the comments!