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Testosterona y glóbulos rojos en hombres trans: el 38 % superó el umbral masculino de eritrocitosis en 10 años

Eritrocitosis en una gran cohorte de hombres trans que usan testosterona: un estudio de seguimiento a largo plazo sobre prevalencia, determinantes y años de exposición

Estudios de cohorte y registrosHormonas cruzadas
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

  • De 1.073 hombres trans con testosterona, el 11 % tuvo la sangre demasiado espesa (más de la mitad del volumen de la sangre formado por glóbulos rojos) en dos análisis según los estándares masculinos; el 3,7 % y el 0,5 % superaron límites más altos.
  • El 24 % tuvo al menos un análisis de sangre por encima del límite masculino.
  • De media, la proporción de la sangre formada por glóbulos rojos subió del 39 % antes del tratamiento al 45 % tras un año, y luego subió solo ligeramente a lo largo de 20 años.
  • Entre los 776 hombres con datos iniciales, la probabilidad de superar alguna vez el límite masculino llegó al 38 % tras 10 años y al 50 % tras 14 años.
  • Las inyecciones de testosterona de acción prolongada se asociaron con unas 3 veces más probabilidades de sangre demasiado espesa que el gel; fumar (unas dos veces más probabilidades), el mayor peso, la mayor edad de inicio y las afecciones pulmonares también aumentaron el riesgo.
  • Usando en cambio el límite normal para las mujeres, el 26 % habría cumplido el criterio en dos análisis, dijeron los autores en una respuesta a una carta publicada.
  • El estudio midió solo análisis de sangre, no hechos reales de salud como coágulos o infartos.

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.