New findings indicate that extended hormone therapy in transgender people can significantly alter body composition and elevate the risk for cardiovascular disease, especially among transgender men.
Recent research conducted by Karolinska Institutet reveals that prolonged sex hormone treatment in transgender individuals can produce notable changes in body composition and cardiovascular disease risk factors, particularly for transgender men. This study was published in the Journal of Internal Medicine.
“We discovered that transgender men undergoing testosterone treatment experienced a 21% average increase in muscle volume over a span of six years, but there was also a concerning 70% rise in abdominal fat,” states Tommy Lundberg, an associate professor from the Department of Laboratory Medicine, Karolinska Institutet. “Additionally, these individuals showed higher liver fat levels and increased ‘bad’ LDL cholesterol, which could heighten cardiovascular disease risks.”
The study observed 17 adult transgender men and 16 transgender women receiving testosterone and estrogen treatments, respectively. Researchers utilized magnetic resonance imaging (MRI) to analyze body composition and evaluated metabolic risk factors through blood tests, blood pressure assessments, and evaluations of vascular stiffness. The assessments were performed prior to initiating hormone therapy, and then again after one year and five to six years.
The findings indicate that long-term hormone therapy brings about significant changes in body composition and metabolic risks, especially for transgender men. Fat volume changes persisted over time, while the most noticeable increases in muscle mass and strength were recorded in the first year of treatment.
“Earlier studies have mostly focused on short-term effects, typically extending up to two years,” explains Tommy Lundberg. “Our findings highlight the need for ongoing monitoring of the long-term health impacts of hormone therapy in transgender individuals to mitigate risks of cardiovascular disease and other health complications.”
In transgender women treated with estrogen, the changes were less significant. Over five years, muscle volume decreased by an average of seven percent, but muscle strength remained stable. While total fat volume increased, abdominal fat gain was lesser.
The study also included tissue samples from muscle, fat, and skin. The next phase involves analyzing these samples to better understand the relationship between genetic sex and sex hormones. Researchers are investigating how hormone treatment influences gene expression in skeletal muscle and what mechanisms are involved in changes to adipose tissue.
“Beyond health implications, our research enhances the understanding of realistic outcomes associated with masculinizing and feminizing effects of hormone treatments,” adds Tommy Lundberg. “However, some of these changes were relatively minor, suggesting caution when forming expectations about significant long-term alterations in this patient group.”
The research received financial support from Region Stockholm, the Thuring Foundation, the 1.6 Million Club, the Centre for Innovative Medicine at Karolinska Institutet, the Swedish Research Council, the Swedish Medical Association, the Novo Nordisk Foundation, and the European Foundation for Studies of Diabetes.
Two of the co-authors are affiliated with AMRA Medical AB. Tommy Lundberg has been reimbursed for providing expert insights on skeletal muscle transformations in transgender individuals and for travel related to speaking engagements on this subject.
