Summary
Testosterone makes the body produce more red blood cells. Blood that becomes too thick raises the risk of clots, heart attack and stroke. Amsterdam doctors reviewed blood tests from 1,073 trans men on testosterone over up to 20 years. About one in nine had repeatedly high levels by male standards. The chance of ever crossing the limit kept rising for years, reaching 38% after a decade, so someone stable for years can still develop it. Long-acting injections, smoking, higher weight, older age and lung disease raised the risk. The authors advise checking blood for as long as testosterone is used. More than half of the clinic's trans men were left out for missing data. Using the normal limits for women would label far more people as affected (26%, the authors said in a reply to a letter), so the true scale may be higher.
Key findings
- من بين 1,073 رجلاً متحولاً على التستوستيرون، كان لدى 11% دم أكثر سماكة من اللازم (أكثر من نصف حجم الدم كريات حمراء) في فحصين وفق معايير الذكور؛ وتجاوز 3.7% و0.5% حدوداً أعلى.
- كان لدى 24% فحص دم واحد على الأقل فوق حد الذكور.
- في المتوسط، ارتفعت نسبة الدم المكوّنة من كريات حمراء من 39% قبل العلاج إلى 45% بعد سنة، ثم ارتفعت قليلاً فقط على مدى 20 سنة.
- بين الـ 776 رجلاً الذين لديهم بيانات بداية، بلغ احتمال تجاوز حد الذكور في أي وقت 38% بعد 10 سنوات و50% بعد 14 سنة.
- ارتبطت حقن التستوستيرون طويلة المفعول بنحو 3 أضعاف احتمالات الدم الأسمك مقارنة بالجل؛ ورفع التدخين (نحو ضعفي الاحتمالات) والوزن الأعلى والعمر الأكبر عند البدء وأمراض الرئة الخطر أيضاً.
- باستخدام الحد المعتاد للنساء بدلاً من ذلك، كان 26% سيستوفون المعيار في فحصين، بحسب ما قال المؤلفون في رد على رسالة منشورة.
- قاست الدراسة فحوص الدم فقط، لا أحداثاً صحية فعلية مثل الجلطات الدموية أو النوبات القلبية.
Abstract
CONTEXT: Erythrocytosis is a known side effect of testosterone therapy that can increase the risk of thromboembolic events. OBJECTIVES: To study the prevalence and determinants in the development of erythrocytosis in trans men using testosterone. METHODS: A 20-year follow-up study in adult trans men who started testosterone therapy and had monitoring of hematocrit at our center (n = 1073). RESULTS: Erythrocytosis occurred in 11% (hematocrit > 0.50 L/L), 3.7% (hematocrit > 0.52 L/L), and 0.5% (hematocrit > 0.54 L/L) of trans men. Tobacco use (odds ratio [OR] 2.2; 95% CI, 1.6-3.3), long-acting undecanoate injections (OR 2.9; 95% CI, 1.7-5.0), age at initiation of hormone therapy (OR 5.9; 95% CI, 2.8-12.3), body mass index (BMI) (OR 3.7; 95% CI, 2.2-6.2), and pulmonary conditions associated with erythrocytosis and polycythemia vera (OR 2.5; 95% CI, 1.4-4.4) were associated with hematocrit > 0.50 L/L. In the first year of testosterone therapy hematocrit increased most: 0.39 L/L at baseline to 0.45 L/L after 1 year. Although there was only a slight continuation of this increase in the following 20 years, the probability of developing erythrocytosis still increased (10% after 1 year, 38% after 10 years). CONCLUSION: Erythrocytosis occurs in trans men using testosterone. The largest increase in hematocrit was seen in the first year, but also after the first years a substantial number of people present with hematocrit > 0.50 L/L. A reasonable first step in the care for trans men with erythrocytosis while on testosterone is to advise them to quit smoking, to switch to a transdermal administration route, and if BMI is high, to lose weight.
Conclusion
Erythrocytosis occurs in trans men using testosterone. The largest increase in hematocrit was seen in the first year, but also after the first years a substantial number of people present with hematocrit > 0.50 L/L. A reasonable first step in the care for trans men with erythrocytosis while on testosterone is to advise them to quit smoking, to switch to a transdermal administration route, and if BMI is high, to lose weight. The authors add that regular hematocrit control seems warranted for as long as testosterone is used.