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Transgender women on HT have lower bone density, more fat mass than men



Low bone mineral density was common in a group of transgender women receiving hormone therapy, according to findings from a recent Brazilian study.

“Lumbar spine density was lower than in reference men but similar to that of reference women,” said Tayane Muniz Fighera, MD, speaking at the annual meeting of the Endocrine Society.

Lower lumbar spine density in transgender women was associated with lower appendicular lean mass and higher total fat mass, with correlation coefficients of 0.327 and 0.334, respectively (P = .0001 for both).

Dr. Fighera and her colleagues looked at the independent contribution of age, estradiol level, appendicular lean mass, and fat mass to bone mineral density (BMD) in the transgender patients, using linear regression analysis. Total fat mass and appendicular lean mass were both independent predictors of bone mineral density (P = .001 and P = .022, respectively). For femur BMD, age, and total fat mass were predictors (P = .001 and P = .000, respectively).

The study aimed to assess bone mineral density as well as other aspects of body composition within a cohort of transgender women initiating hormone therapy in order to determine how estrogen therapy affected BMD and assess the prevalence of low bone mass among this population.

The hypothesis, said Dr. Fighera, was that hormone therapy for transgender women might decrease muscle mass and increase fat mass, “leading to less bone surface strain and smaller bone size over time,” said Dr. Fighera, of the Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.

Previous work has shown conflicting results, she said. “While some studies report that estrogen therapy is able to increase bone mass, others have observed no difference in BMD” despite the use of hormone therapy. The studies showing an association between estrogen therapy and decreased bone mass were those that followed patients for longer periods of time – 2 years or longer, she said.


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