Conference Coverage

Hormones taken by transgender female teens affect fat levels, muscle mass



– Transgender adolescents who take hormones and gonadotropin-releasing hormone analogs have body composition measures that vary between those seen in control females and males, according to results of a pilot study presented during a poster session at the annual meeting of the Endocrine Society.

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“Between 0.7% and 1.6% of adolescents in the United States identify as transgender,” Natalie Nokoff, MD, of the University of Colorado Anschutz, so there will be a large population of teens who may be taking gender-affirming medications over the course of their lives. At the transgender care clinic at the university, the population of these patients has recently climbed to nearly 1,000 patients.

“There have been a few studies that have come out about the health of transgender female adults” – individuals born with a male sex but a female gender identity – for whom standard of care includes blocking puberty with a gonadotropin-releasing hormone (GnRH) analog to prevent development of male secondary sex characteristics at puberty, said Dr. Nokoff. Estradiol is used later, as well.

The impact of these regimens on overall health was examined in a cross-sectional pilot study of 14 adolescent transgender females, average age 16 years. The patients had been on estradiol for an average of about a year. Control groups were adolescent males and females who were matched by age and body mass index.

“Really, my main question of interest as a pediatric endocrinologist is what is the impact of not only hormones on short- and long-term heart health, and diabetes risk, and long-term health, but also, what [is] the impact of the puberty blockers, or GnRH analogs, with subsequent hormones on health as well,” said Dr. Nokoff. “That’s really the understudied area – what people don’t understand.

“We found that there were several differences in terms of markers of metabolic health between transgender females on estradiol” and the controls, Dr. Nokoff said. “Most notably ... they had a higher (level of) body fat than males, and lower (level) than females” in the control group.

The difference between transgender females and control females and control males for percent body fat was statistically significant (P = .03 and .003, respectively). Differences in lean body mass were also significant when comparing the transgender females and the control males and females (P = .001 and .001, respectively).

“In terms of insulin sensitivity, our other outcome of interest, there was no difference in insulin sensitivity between transgender females and control females, but they were more insulin resistant – or less insulin sensitive – than control males.” This latter difference was statistically significant (P = .01).

Dr. Nokoff reported that she had no relevant conflicts of interest.

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