Questions Persist About Effects of Testosterone Therapy in Transgender Men

Vial and syringe
Vial and syringe
A lack of data prevents endocrinologists from fully understanding the long-term risks of therapy in this patient population.

The management of transgender patients has become more common for endocrinologists. However, there is a significant lack of controlled clinical trials to help guide clinicians on how best to prescribe hormone therapy and manage the potential risks and benefits, according to a review article published in The Lancet Diabetes & Endocrinology.1

“I was invited to write this review [of testosterone therapy for transgender men] because transgender medicine is a hot topic in endocrinology and because many endocrinologists need more training and knowledge in transgender medicine,” said Michael Irwig, MD, associate professor of medicine at the George Washington (GW) University School of Medicine and Health Sciences and director of the Andrology Center at the GW Medical Faculty Associates in Washington, D.C.

The review evaluated published literature on testosterone therapy in transgender men, principally from the last 15 years. The goal of testosterone therapy in this patient population is usually to achieve serum testosterone concentrations in the male reference range. While testosterone therapy overall appears to be quite safe in the short term in transgender men, the long-term effects have not been thoroughly evaluated, Dr Irwig explained

“Most endocrinologists care for fewer than 5 transgender patients, and many are looking to increase their cultural competency in the area,” he told Endocrinology Advisor. “It is important for endocrinologists to counsel transgender men about what to expect in terms of benefits and potential side effects on testosterone therapy.”

Benefits and Risks of Testosterone Therapy

Dr Irwig noted that testosterone therapy is prescribed for transgender men in order to obtain male secondary sexual characteristics, to improve well-being, and to decrease gender dysphoria.

Within several months of starting testosterone therapy, transgender men begin to notice many desired effects, such as increased facial and body hair, increased lean mass and strength, decreased fat mass, and a deeper voice. The review also suggests that these men usually experience increased sexual desire, cessation of menses, clitoral enlargement, and lower rates of gender dysphoria, as well as less perceived stress, anxiety, and depression after receiving testosterone therapy. An additional benefit of testosterone therapy is a reduction in the risk for breast cancer with or without a mastectomy.

However, potential undesired effects and risks include acne, alopecia, lower HDL cholesterol, higher triglycerides, and a possible increase in systolic blood pressure, according to the review. While most of the effects of testosterone therapy develop soon after starting therapy, facial hair and alopecia appear to continue to develop after 1 year.

The review included articles published in English and Spanish from January 2000 to May 2015, as were a select number of older publications, about testosterone therapy in transgender men. Articles on other populations receiving testosterone therapy were also included for comparisons.

Dr Irwig found high-quality data are lacking. He noted that problems in obtaining these data stem from a lack of randomized controlled trials due to ethical issues, suboptimal control groups, and loss to follow-up. Other issues also include difficulties in recruiting representative samples. Subsequently, the long-term consequences of therapy are unknown.

Currently, there is also a lack of hard data on how many individuals are transgender. The true prevalence of transgenderism is difficult to determine due to the fact that some transgender individuals may not come to terms with their gender identity until later in life. In addition, some individuals may not ever openly identify as transgender for a host of reasons, including societal pressures and stigmatization. One population-based household probability study of more than 28 000 adults in Massachusetts in 2010 showed that 1 in 215 people identified as transgender.2