E-Poster Presentation ESA-SRB-ANZBMS 2021

Background: Hormone therapy is an effective and important part of gender affirming care for many trans and gender diverse (TGD) individuals. In cisgender women, exogenous oestrogen carries a well-recognised dose-dependent thrombotic risk, heightened in the presence of other venous thromboembolism (VTE) risk factors such as inherited thrombophilia and obesity. The prothrombotic risk of testosterone replacement is less well established. The prevalence of VTE during hormone therapy, and changes in risk over time, remain unknown in TGD individuals.

Case Series: VTE in six TGD individuals is presented with clinical and management features summarised in the table. Patients 1 to 4 developed VTE during gender affirming hormone therapy. Patient 1 developed lower limb deep vein thrombosis (DVT) after one month of transdermal oestradiol, whereas Patients 2 to 4 developed VTE after 1-19 years on oral oestrogen. Patient 2 developed DVT in the context of oestradiol dose increasing from 4 to 5 mg/day due to low serum oestradiol (187 pmol/L). Patient 3 had previous provoked DVT following orchidectomy. Patient 4 was lost to follow-up prior to VTE presentation. Patient 5 was on intramuscular testosterone for Klinefelter syndrome when they developed VTE and later commenced oestrogen as part of gender transition. All patients were anticoagulated: Patient 1 with warfarin and others with direct oral anticoagulants. Patient 2 discontinued hormonal therapy due to concerns regarding alopecia from her anticoagulation. Patient 5 ceased testosterone and commenced oestrogen as part of her transition.

Conclusion: Hormone therapy carries a risk of VTE in TGD individuals. Clinical and mechanistic studies are needed to further our understanding of VTE risk and factors which may guide VTE risk stratification and management. Further research is required to inform optimal management of hormone therapy and anticoagulation in TGD individuals with and without a prior history of, or risk factors for, VTE.