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Testosteron höjde röda blodkroppar hos transmän: 38 % passerade mäns erytrocytosgräns inom 10 år

Erytrocytos i en stor kohort av transmän som använder testosteron: en långtidsuppföljning av förekomst, bestämningsfaktorer och exponeringsår

Kohort- & registerstudierKönshormoner
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 transmän på testosteron hade 11 % för tjockt blod (mer än hälften av blodvolymen bestod av röda blodkroppar) vid två prov enligt manliga normer. 3,7 % och 0,5 % passerade högre gränser.
  • 24 % hade minst ett blodprov över den manliga gränsen.
  • I genomsnitt steg andelen av blodet som består av röda blodkroppar från 39 % före behandling till 45 % efter ett år, och steg sedan bara något över 20 år.
  • Bland de 776 männen med startdata nådde chansen att någonsin gå över den manliga gränsen 38 % efter 10 år och 50 % efter 14 år.
  • Långverkande testosteroninjektioner hängde samman med cirka 3 gånger högre odds för för tjockt blod jämfört med gel. Rökning (cirka dubbla oddsen), högre vikt, högre startålder och lungtillstånd höjde också risken.
  • Med den normala gränsen för kvinnor i stället skulle 26 % ha kvalificerat sig vid två prov, sa författarna i ett svar på ett publicerat brev.
  • Studien mätte bara blodprover, inte faktiska hälsohändelser som blodproppar eller hjärtinfarkter.

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.