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• Posted November 28, 2023

Testosterone Therapy for Transgender Patients May Be Safer Than Thought

Transgender people transitioning to male (transmasculine) identity typically take testosterone therapy as part of the process.

There have been worries that the treatment might spur erythrocytosis, an abnormally high concentration of red blood cells in blood that could prove dangerous.

But new research should help allay those fears: The largest study on the subject to date finds no significant risk.

“Providers should feel more comfortable prescribing testosterone when it is indicated. Patients and the families of patients should feel reassured regarding at least this one source of anxiety about treatment," said study senior author Dr. Joshua Safer. He's executive director of the Mount Sinai Center for Transgender Medicine and Surgery in New York City.

The new research was published Nov. 27 in The Journal of Clinical Endocrinology and Metabolism.

The study involved nearly 6,700 transmasculine patients being treated with injectable testosterone across the United States. Safer's team tracked hematocrit, a standard test measuring levels of red blood cells, and compared those results to each patient's blood levels of testosterone.

The result: People on testosterone therapy did have slightly higher hematocrit, the team found, but it never reached levels likely to be clinically significant.

Less than 1% of the transmasculine people tested had a hematocrit exceeding 54% -- the level at which doctors recommend patients receive treatment for erythrocytosis.

Those numbers are smaller than results from other studies, Safer's group noted.

"These results should help providers feel more comfortable prescribing testosterone as part of GAHT [gender-affirming hormone therapy],” the study first author, Nithya Krishnamurthy, a second-year medical student at Icahn Mount Sinai, said in a Mount Sinai news release.

Safer agreed.

“A major concern of patients, providers, and parents is the safety of hormone therapy for transgender and gender-diverse people," he said in the news release. "The findings from this study represent very important reassurance regarding the safety of testosterone as masculinizing treatment."

More information

Find out more about the medical care of transgender people at the Association of American Medical Colleges.

SOURCE: Mount Sinai Health System, news release, Nov. 27, 2023