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テストステロンでトランス男性の赤血球値が上昇：10年以内に38%が男性の赤血球増加症の基準を超えた

テストステロンを使用するトランス男性の大規模コホートにおける赤血球増加症：有病率、決定因子、曝露年数に関する長期追跡研究

コホート研究とレジストリ研究性別適合ホルモン療法
Authors
Milou Cecilia Madsen, Dennis van Dijk, Chantal M. Wiepjes, Elfi B. Conemans, Abel Thijs, Martin den Heijer
Journal
The Journal of Clinical Endocrinology & Metabolism
Year
2021
Source
https://doi.org/10.1210/clinem/dgab089

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

  • テストステロンを使っているトランス男性1,073人のうち、11%が、男性の基準で、2回の検査で血液が濃すぎる状態（血液量の半分以上が赤血球）でした。より高い基準を超えたのは3.7%と0.5%でした。
  • 24%には、男性の基準を超える血液検査が少なくとも1回ありました。
  • 平均すると、血液中の赤血球の割合は、治療前の39%から1年後には45%に上がり、その後20年間でわずかに上がるだけでした。
  • 開始時のデータがあった男性776人では、男性の基準を超える確率は、10年後に38%、14年後に50%に達しました。
  • 長時間作用型のテストステロン注射は、ジェルと比べて、血液が濃すぎるオッズが約3倍と関連しており、喫煙（オッズ約2倍）、体重の増加、開始時の年齢の高さ、肺の病気もリスクを高めました。
  • 著者らは、公表された書簡への返答の中で、女性の通常の基準を代わりに使うと、2回の検査で26%が該当したと述べました。
  • この研究が測定したのは血液検査だけで、血栓や心臓発作などの実際の健康上の事象は測定していません。

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.