Long-term effects and side effects of cross-sex hormone treatment in transsexual persons are not well known.

The aim of this study is to describe the effects and side effects of cross-sex hormone therapy in both transsexual men and women.

Hormone levels were measured by immunoassays. Physical health was assessed by physical examination and questionnaires on general health and specific side effects, areal bone parameters by dual energy X-ray absorptiometry.

Single center cross-sectional study in 100 transsexual persons post-sex reassignment surgery and on average 10 years on cross-sex hormone therapy.

Transsexual men did not experience important side effects such as cardiovascular events, hormone-related cancers, or osteoporosis. In contrast, a quarter of the transsexual women had osteoporosis at the lumbar spine and radius. Moreover, 6% of transsexual women experienced a thromboembolic event and another 6% experienced other cardiovascular problems after on average 11.3 hormone treatment years. None of the transsexual women experienced a hormone-related cancer during treatment.

Cross-sex hormone treatment appears to be safe in transsexual men. On the other hand, a substantial number of transsexual women suffered from osteoporosis at the lumbar spine and distal arm. Twelve percent of transsexual women experienced thromboembolic and/or other cardiovascular events during hormone treatment, possibly related to older age, estrogen treatment, and lifestyle factors. In order to decrease cardiovascular morbidity, more attention should be paid to decrease cardiovascular risk factors during hormone therapy management.