High hematocrit levels rare for adults receiving gender-confirming testosterone therapy
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Key takeaways:
- High hematocrit levels were observed among 8.4% of adults receiving gender-confirming testosterone therapy.
- Intramuscular testosterone was linked to higher hematocrit levels than transdermal testosterone.
Fewer than 1% of adults receiving exogenous testosterone for gender-confirming hormone therapy have a hematocrit level above the norm of 54%, according to data published in The Journal of Clinical Endocrinology & Metabolism.
“Our study found that the number of patients on testosterone therapy with abnormal red blood cell elevations were lower than previously reported in smaller studies,” Nithya Krishnamurthy, BA, a second-year medical student at Icahn School of Medicine at Mount Sinai, told Healio. “The low prevalence of this clinically meaningful change in hematocrit level should provide reassurance for patients and their families about the safety of testosterone therapy.”
Krishnamurthy and colleagues conducted a cross-sectional analysis of laboratory values from adults aged 18 to 65 years prescribed testosterone therapy through Plume, a telehealth service providing gender-confirming HT in the U.S. Adults with an active prescription for testosterone who had at least one testosterone and hematocrit level available were included in the study. Researchers obtained the most recent laboratory value for each participant as of June 2023.
There were 6,670 adults included in the study (mean age, 27 years). Of the group, 8.4% had a hematocrit level of at least 50%, 2.7% had a hematocrit level of 52% or higher, and 0.9% of adults had a hematocrit level of at least 54%. Mean hematocrit levels increased with older age. Adults aged 51 to 65 years had a mean hematocrit of 45.44% compared with 45.2% for those aged 31 to 50 years and a mean hematocrit of 44.56% for adults aged 18 to 30 years.
Of the study population, 41.2% had a testosterone level of 600 ng/dL or higher. When participants were categorized into groups based on testosterone thresholds of 50 ng/dL, the absolute difference in hematocrit levels was small. No difference in hematocrit was observed for adults with a testosterone level of 650 ng/dL to 700 ng/dL, which is the higher end of the target range in the Endocrine Society’s guidelines, and those with a testosterone level of 700 ng/dL to 1,000 ng/dL, which is the higher end of the normal level.
Mean hematocrit levels were higher for adults receiving intramuscular testosterone vs. transdermal testosterone (44.96% vs. 43.41%; P < .001). Those receiving intramuscular testosterone also had a higher mean testosterone than those receiving transdermal testosterone (590.85 ng/dL vs. 460.95 ng/dL; P < .001). Serum testosterone level and administration route were both associated with hematocrit in linear regression analysis (P < .001 for both).
“Further research should assess the influence of factors other than testosterone that might potentiate secondary erythrocytosis, such as being overweight, smoking tobacco or using alcohol,” Krishnamurthy said.
For more information:
Nithya Krishnamurthy, BA, can be reached at nithya.krishnamurthy@icahn.mssm.edu.
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