August 06, 2018
2 min read

For transgender men, testosterone formulations equally safe, effective

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In young transgender men, long-acting testosterone undecanoate and testosterone enanthate were equally effective and safe when administered for 5 years, according to research published in Clinical Endocrinology.

“Some gender nonconforming individuals require transgender hormonal therapy to align appearance with gender identity features of the affirmed gender,” Giulia Gava, MD, of the department of gynecology and physiopathology of human reproduction at S. Orsola Malpighi Hospital and the department of surgical and medical sciences at the University of Bologna, said in the study background. “Testosterone is the key hormone required by transmen. This can be administered through parenteral or transdermal preparations, with the aim of achieving and maintaining serum [testosterone] within the normal male range. Amenorrhea, increased muscle mass and strength, production of male-pattern body hair growth and deepening of the voice are some of the desired effects of [transgender hormone therapy] in these subjects.”

In a retrospective, observational pilot study, researchers recruited 50 transgender men aged 21 to 42 years at the time of their routine clinical examination. Eligible participants had a diagnosis of gender dysphoria and were prescribed transgender hormone therapy for 5 years. None of the participants underwent genital surgery prior to testosterone treatment.

Within the cohort, 25 participants were prescribed 1,000 mg intramuscular testosterone undecanoate at baseline and 6 weeks, and then every 12 to 16 weeks, and 25 participants were prescribed 250 mg intramuscular testosterone enanthate every 3 to 4 weeks.

At baseline and every subsequent 12 months, participants fasted for 12 hours overnight and were tested for various biochemical and hormonal parameters. The researchers also assessed anthropometric traits, body composition and blood pressure at baseline and then every year thereafter. The global satisfaction of the patient population was evaluated using the visual analogue scale at baseline and after 1 and 5 years.

The researchers found significant increases in hematocrit and hemoglobin (P < .0001) at the 5-year follow up, with no significant disparities between the two groups, and measurements consistently within the physiologic range. Throughout the study period, neither group demonstrated changes in activated partial thromboplastin time. Significant and advancing increases in liver enzymes were seen during follow-up, but this measure also remained within the physiologic range, according to the researchers.

Researchers also observed increases in total cholesterol in both groups over 5 years (P < .05); however, the testosterone enanthate group showed an increase in HDL cholesterol only at year 1 (P = .004) that stabilized by year 5. Triglyceride levels increased in both groups during follow-up; however, the increase was significant only in the testosterone enanthate group (P < .05) and stayed within the normal range.


Researchers did not observe changes from baseline for measures of fasting glucose or insulin resistance in either group.

At 1 year, researchers noted significant decreases in luteinizing hormone levels vs. baseline for both groups, with no between-group difference. Only patients who underwent gonadectomy surgery showed an increases in gonadotropins. Researchers also observed an increase in mean serum testosterone levels, measured prior to the next injection at year 1, staying through normal male range for both groups throughout follow-up. Estrogen levels were decreased from baseline at year 1 and progressively decreased at year 5 in both groups, particularly in participants who had undergone gonadectomy.

Both groups reported being “highly satisfied” with testosterone treatment (P < .001) during follow-up.

No death, myocardial infarction, stroke, venous thromboembolism, pulmonary or microembolism, or other adverse events were documented for either group.

“Our study suggests that administration of either [testosterone undecanoate] or [testosterone enanthate] for 5 years in healthy and relatively young transmen is both safe and effective,” the researchers wrote. “Further studies with a greater number of subjects, including the older population, with longer follow-ups, are required to definitively assess the safety of [testosterone] treatment in transmen.” – by Jennifer Byrne

Disclosure: Endocrine Today was unable to determine relevant financial disclosures at publication.