OBJECTIVE: Transgender and gender-diverse individuals undergoing estradiol therapy for gender affirmation are typically treated with oral or transdermal estradiol, with transdermal estradiol recommended for those aged >
45 years. There are limited data evaluating estradiol gel in gender-affirming hormone therapy regimens. We aimed to assess the serum estradiol concentrations achieved with estradiol 0.06% gel in transgender and gender-diverse adults. DESIGN: Retrospective cross-sectional audit of transgender and gender-diverse adults at endocrine clinics in Melbourne, Australia. PATIENTS: Eighty-one adults treated with estradiol 0.06% gel. MEASUREMENTS: Outcomes were estradiol 0.06% gel dose, serum estradiol concentration and proportion of individuals achieving target serum estradiol concentrations in consensus guidelines. RESULTS: Median serum estradiol concentration was 396 pmol/L (233-681) on 1.5 mg (1.5-2.25) estradiol 0.06% gel daily. Forty-six percent of individuals achieved serum estradiol concentrations within target range (250-600 pmol/L) of Australian consensus guidelines
27% were below range and 27% were above range. There was a weak positive correlation between estradiol gel dose and serum estradiol concentration (r = 0.23, p = 0.04). CONCLUSION: Estradiol 0.06% gel achieves target serum estradiol concentrations in a significant proportion of transgender and gender-diverse adults. This represents an alternative estradiol formulation for individuals desiring estradiol therapy for gender affirmation.