Aims: Standard estradiol formulations used in menopausal hormone therapy are typically administered to transgender and gender diverse individuals seeking feminisation, though there are currently limited data evaluating transdermal estradiol formulations in gender-affirming hormone therapy regimens. We aimed to assess the serum estradiol concentrations achieved with estradiol 0.06% gel (EstroGel) in trans and gender diverse individuals.
Methods: A retrospective cross-sectional analysis was undertaken of transgender and gender diverse individuals treated with estradiol gel at Endocrine clinics in Melbourne, Australia. Serum estradiol concentration was measured via immunoassay. Primary outcomes were estradiol gel dose and serum estradiol concentration.
Results: Eighty-one individuals treated with estradiol gel were included. Median age was 29 years (23-40), and duration of feminising hormone therapy was 29 months (17-48). Median serum estradiol concentration was 396 pmol/L (233-681) on 1.5 mg (1.5-2.25) (equivalent to 2 pumps) estradiol gel daily. Thirty-seven (46%) individuals achieved serum estradiol concentrations within the recommended target range of 250-600 pmol/L. There was a weak positive correlation between estradiol gel dose and serum estradiol concentration (r=0.23, p=0.04). Compared to a group of 259 individuals treated with oral estradiol, median serum estradiol concentration achieved was higher in individuals treated with estradiol gel (396 vs. 328 pmol/L, p<0.01). Thirteen individual laboratory results with supraphysiological serum estradiol concentrations (2000-6000 pmol/L) and documentation of skin contamination with estradiol gel at venepuncture site were excluded.
Conclusions: Estradiol 0.06% gel achieves serum estradiol concentrations in the recommended range in Australian consensus guidelines though there is significant interindividual variability, with a weak correlation between estradiol gel dose and serum estradiol concentration. Estradiol 0.06% gel represents an alternative estradiol formulation for trans and gender diverse individuals seeking feminisation.