Erythrocytosis in a Large Cohort of Trans Men Using Testosterone: A Long-Term Follow-Up Study on Prevalence, Determinants, and Exposure Years.

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.

• Authors: Milou Cecilia Madsen, Dennis van Dijk, Chantal Maria Wiepjes, Elfi Barbara Conemans, Abel Thijs, Martin den Heijer
• Journal: The Journal of clinical endocrinology and metabolism (J Clin Endocrinol Metab) Vol. 106 Issue 6 Pg. 1710-1717 (05 13 2021) ISSN: 1945-7197 [Electronic] United States
• PMID: 33599731 (Publication Type: Journal Article)
• Copyright: © The Author(s) 2021. Published by Oxford University Press on behalf of the Endocrine Society.

Chemical References

• Testosterone

Topics

• Adolescent
• Adult
• Cohort Studies
• Female
• Follow-Up Studies
• Gender Dysphoria (drug therapy, epidemiology)
• Hormone Replacement Therapy (adverse effects, methods, statistics & numerical data)
• Humans
• Longitudinal Studies
• Male
• Netherlands (epidemiology)
• Polycythemia (chemically induced, epidemiology)
• Prevalence
• Risk Factors
• Sex Reassignment Procedures (adverse effects, methods, statistics & numerical data)
• Testosterone (therapeutic use)
• Time Factors
• Transgender Persons
• Transsexualism (drug therapy, epidemiology)
• Young Adult