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La testostérone a élevé les globules rouges des hommes trans : 38 % ont franchi le seuil d'érythrocytose en 10 ans

Érythrocytose dans une grande cohorte d'hommes trans sous testostérone : une étude de suivi à long terme sur la prévalence, les déterminants et les années d'exposition

Études de cohorte & registresHormones croisées
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

  • Sur 1 073 hommes trans sous testostérone, 11 % avaient un sang trop épais (plus de la moitié du volume sanguin constituée de globules rouges) lors de deux analyses selon les normes masculines ; 3,7 % et 0,5 % dépassaient des limites plus élevées.
  • 24 % avaient au moins une analyse sanguine au-dessus de la limite masculine.
  • En moyenne, la part du sang constituée de globules rouges est passée de 39 % avant le traitement à 45 % après un an, puis n'a que légèrement augmenté sur 20 ans.
  • Parmi les 776 hommes ayant des données de départ, la probabilité de dépasser un jour la limite masculine atteignait 38 % après 10 ans et 50 % après 14 ans.
  • Les injections de testostérone à action prolongée étaient liées à environ 3 fois plus de probabilités de sang trop épais que le gel ; le tabagisme (environ deux fois plus de probabilités), le poids plus élevé, un âge de début plus élevé et les maladies pulmonaires augmentaient aussi le risque.
  • En utilisant plutôt la limite normale pour les femmes, 26 % auraient été concernés lors de deux analyses, ont dit les auteurs dans une réponse à une lettre publiée.
  • L'étude n'a mesuré que des analyses sanguines, pas des événements de santé réels comme des caillots sanguins ou des crises cardiaques.

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.