Endocrine Abstracts

Context: Little research has been performed on hemostatic changes in transgender subjects receiving cross-sex hormone treatment (CSHT), despite the fact that several studies implicate an increased risk of venous thrombosis (VT) associated with hormones.

Objective: Assessing whether coagulation is relevantly influenced by prolonged CSHT, stratified for the different treatment modalities, in transgenders.

Design and main outcome: Prospective study on CSHT-induced changes of hemostatic variables in transgenders. The main outcome measures were mean paired differences in factor II, IX and XI, protein C and S, fibrinogen, and activated protein C resistance (APCR) over a period of 12 months of CSHT.

Participants: Eighty two subjects were included, of which 41 male-to-female (MtF) and 41 female-to-male (FtM), who used CSHT for 12 months.

Intervention: Oral or transdermal 17β-estradiol, combined with cyproterone acetate, in MtFs and testosterone gel or injections in FtMs.

Results: In MtFs, protein C decreased on average by 0.078 U/ml (95% CI 0.042,0.111), while factor IX and XI increased by 0.152 (95% CI −0.235, −0.069) and 0.148 U/ml (95%CI −0.214, −0.082), respectively. No change was observed in the other factors. No difference in changes between the treatment modalities was observed. Conversely, FtMs only experienced an average increase of 0.104 U/ml (95% CI −0.215, 0.007) in factor IX. None of the other investigated factors showed any change in this group. Several factors changed differently for the treatment modalities. The results will be extended with more patients and hemostatic variables (APCR, TFPI). The complete set of results will be analyzed for the role of treatment modality, age and other relevant factors in these changes.

Conclusions: CSHT induces relevant prothrombotic changes in multiple hemostatic factors in MtFs. In FtMs, no clear effect of CSHT was observed. The change in some variables is modified by the different treatment modalities in FtMs, but not in MtFs.