Oral Presentation ESA-SRB-AOTA 2019

Global coagulation assays in transgender women (#52)

Ada S Cheung 1 2 , Hui Yin Lim 3 4 5 , Niloufar Torkamani 1 2 , Max Rainier 1 , Mathis Grossmann 1 2 , Harshal Nandurkar 5 , Jeffrey D Zajac 1 2 , Prahlad Ho 3 5
  1. Trans Health Research Group, Department of Medicine, The University of Melbourne, Heidelberg, VIC, Australia
  2. Department of Endocrinology, Austin Health, Heidelberg, VIC, Australia
  3. Department of Haematology/Northern Pathology Victoria, The Northern Hospital, Epping, Victoria, Australia
  4. Florey Institute of Neurosciences and Mental Health, The University of Melbourne, Parkville, Victoria, Australia
  5. Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria, Australia

Background: As opposed to standard coagulation tests, global coagulation assays such as thromboelastography (TEG) and thrombin generation may be better surrogate measures of venous and arterial thrombosis risk, adverse effects of estradiol therapy. There is minimal data investigating thrombotic risk of estradiol therapies in transgender women. We hypothesised that transgender women on oral estradiol would have TEG parameters of higher clot strength and lower clot lysis, and higher thrombin generation than those on transdermal estradiol.

Aims: To evaluate global coagulation assays (thromboelastography; thrombin generation using calibrated automated thrombogram (CAT); fibrin generation with overall haemostatic potential (OHP) assay) in transgender women on estradiol therapy.

Methods: This cross-sectional analysis involved transgender women (male-to-female) and cisgender healthy controls. Fasting blood samples were collected and analysed within 4 hours of venepuncture for (i) thromboelastography using citrated whole blood (TEG® 5000), (ii) CAT and (iii) OHP using platelet-poor plasma.

Results: 25 transgender women (mean age 39) were compared to 97 controls (68% female; mean age 43). Fourteen (56%) used oral and 11 used transdermal estradiol. Mean duration of estradiol therapy was similar between oral and transdermal routes (26 vs 34 months; p=0.41). Route of estrogen delivery did not influence any global coagulation assay parameter. Overall, transgender women on estradiol demonstrated increased clot strength (maximum amplitude 65.2 vs 57.9 mm; p<0.001) on whole blood TEG(Table). CAT showed comparable endogenous thrombin potential (ETP) (1399.7 vs 1350.0 nM.min; p=0.41) in the transgender individuals. Interestingly, fibrin generation was reduced in the transgender women (overall coagulation potential 51.9 vs 59.6; p=0.003) with similar overall fibrinolytic potential.

Conclusion: Transgender women on oral and transdermal estradiol had higher whole blood clot strength compared to cisgender controls. Route of delivery did not influence whole blood clot strength. Further study is required with larger sample sizes to assess differing doses of transdermal therapy.

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