per MCW IRB

The specific aim for our study is to measure coagulation system activation and fibrinolysis following transdermal versus sublingual versus oral estradiol versus in transgender women.

Hypothesis: Transdermal estradiol will result in less coagulation system activation and no effect on plasminogen activator inhibitor (PAI-1) or tissue-type plasminogen activator (t-PA). Oral estradiol will result in the most coagulation system activation and effect on PAI-1 and t-PA: Oral estradiol > sublingual estradiol > transdermal estradiol.

A prospective crossover study will include ten subjects given estradiol 1 mg daily and instructed to take it orally, sublingually, or transdermal for 2 months with a 2-week washout period between routes of administration. Labs will be measured 7 times during the study.

Subjects will report to our Adult Translational Research Unit for labs at baseline (2 weeks after HRT washout if needed). Both fibrinolysis and testosterone labs have a diurnal variation. Therefore, fasting labs will be drawn at approximately 8 AM. Five subjects will start oral estradiol and 5 will start sublingual estradiol for 8 weeks. Froedtert's Pharmacy Investigational Drug Service will provide the study estradiol. There will be a 2-week washout period between treatment periods. Fasting labs will be drawn at approximately 8 AM prior to Treatment Period 2. The groups will switch therapy. Those that took oral estradiol during Treatment Period 1 will take sublingual estradiol for 8 weeks. Those that took sublingual estradiol during Treatment Period 1 will take oral estradiol for 8 weeks. Finally, all subjects will start the transdermal for 8 weeks for Treatment Period 3. Final set of labs will be drawn at approximately 8 AM 2 weeks after Treatment Period 3. The investigators will call subjects every 2 weeks to assess their adherence to the treatment protocol and remind them of the importance of allowing the tablet to dissolve when taking estradiol sublingually.

Inclusion Criteria:

• 18 years or older
• Gender identity of male to female or transwoman

Exclusion Criteria:

• Liver disease
• History of blood clot
• Bleeding disorder
• Active or recent (e.g., within the past year) stroke
• Myocardial infarction,
• History of orchiectomy
• History of breast cancer,
• Known sensitivity or allergy to any components of the medications used
• Currently taking a potent CYP3A4 inhibitor or inducer.

Transwoman (gender identity female, assigned male at birth)

All individual participant data that underlie results in a publication.

starting 3 months after publication

IPD will be shared if PI is directly contacted and asked for the above information.