Incidence of thrombophilia and venous thrombosis in transsexuals under cross-sex hormone therapy

ObjectiveTo evaluate the incidence of venous thromboembolism (VTE) in transsexual patients and the value of screening for thrombophilia in this population.DesignRetrospective cohort study.SettingAcademic research institution.Patient(s)Two hundred fifty-one transsexuals (162 male-to-female [MtF] and 89 female-to-male [FtM] transsexuals).Intervention(s)Screening for activated protein C (aPC) resistance, antithrombin III, free protein S antigen, and protein C deficiency.Main Outcome Measure(s)Incidence of thrombophilic defects and VTE during cross-sex hormone therapy.Result(s)Activated protein C resistance was detected in 18/251 patients (7.2%), and protein C deficiency was detected in one patient (0.4%). None of the patients developed VTE under cross-sex hormone therapy during a mean of 64.2 ± 38.0 months. There was no difference in the incidence of thrombophilia comparing MtF and FtM transsexuals (8.0% [13/162] vs. 5.6% [5/89], respectively).Conclusion(s)VTE during cross-sex hormone therapy is rare. General screening for thrombophilic defects in transsexual patients is not recommended. Cross-sex hormone therapy is feasible in MtF as well as in FtM patients with aPC resistance.