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Testosteron økte nivået av røde blodceller hos transmenn: 38 % passerte terskelen for erytrocytose hos menn innen 10 år

Erytrocytose i en stor kohort av transmenn som bruker testosteron: en langtidsoppfølgingsstudie av prevalens, determinanter og eksponeringsår

Kohort- og registerstudierKjønnsbekreftende hormoner
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

  • Av 1 073 transmenn på testosteron hadde 11 % for tykt blod (mer enn halvparten av blodvolumet bestående av røde blodceller) på to prøver etter mannlige standarder. 3,7 % og 0,5 % passerte høyere grenseverdier.
  • 24 % hadde minst én blodprøve over den mannlige grensen.
  • I gjennomsnitt økte andelen av blodet som består av røde blodceller fra 39 % før behandling til 45 % etter ett år, og steg deretter bare litt over 20 år.
  • Blant de 776 mennene med startdata nådde sjansen for noen gang å gå over den mannlige grensen 38 % etter 10 år og 50 % etter 14 år.
  • Langtidsvirkende testosteroninjeksjoner var knyttet til omtrent 3 ganger så stor odds for for tykt blod sammenlignet med gel. Røyking (omtrent dobbelt så stor odds), høyere vekt, høyere startalder og lungetilstander økte også risikoen.
  • Med den vanlige grensen for kvinner i stedet ville 26 % ha kvalifisert på to prøver, sa forfatterne i et svar på et publisert lesebrev.
  • Studien målte bare blodprøver, ikke faktiske helsehendelser som blodpropp eller hjerteinfarkt.

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.