Risk and management of congenital thrombophilia in transgender individuals undergoing gender-affirming hormone therapy

Gender-affirming hormone therapy (GAHT), particularly estrogen-based regimens, is associated with an increased risk of venous thromboembolic events (VTE), which may be exacerbated in individuals with hereditary thrombophilia. Despite this risk, the prevalence and clinical implications of hereditary thrombophilia in transgender individuals remain underexplored. We screened 114 transgender individuals (54 AMAB, 60 AFAB) at the University Hospital of Padua (Italy) for hereditary thrombophilia, including factor V Leiden (FVL), prothrombin G20210A (PT20210A), antithrombin (AT), protein C (PC), and protein S (PS) deficiencies, as well as antiphospholipid antibodies. Hereditary thrombophilia was identified in 9.6% of participants, including two cases of severe thrombophilia. No participants tested positive for antiphospholipid antibodies. Individuals with thrombophilia had a higher prevalence of personal and family history of VTE. Three thrombotic events were recorded prior to GAHT: one transgender woman (heterozygous FVL) with unprovoked lower limb VTE, one transgender man (PC deficiency) with neonatal cerebral ischemia, and one transgender man (heterozygous FVL) with subclavian VTE during chemotherapy. A multidisciplinary approach involving coagulation specialists and endocrinologists was implemented to optimize risk reduction strategies, including tailored GAHT regimens and anticoagulation when necessary. No VTE occurred during follow up. These findings highlight the importance of thrombophilia screening to enable individualized care and enhance the safety of GAHT protocols.