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

OBJECTIVE

To evaluate the incidence of venous thromboembolism (VTE) in transsexual patients and the value of screening for thrombophilia in this population.

DESIGN

Retrospective cohort study.

SETTING

Academic 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.