Bone density rebounds for transgender people during gender-confirming hormone therapy
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Key takeaways:
- Bone mineral density increases in most areas for transgender people during gender-confirming HT.
- Those assigned male at birth have no increase in lumbar spine BMD z score during HT.
Transgender people who use gender-confirming hormone therapy long term have increases in bone mineral density back to levels observed before pubertal suppression, according to findings published in JAMA Pediatrics.
“After long-term use of gender-affirming hormones, z scores in individuals treated with puberty suppression catch up with pretreatment levels, except for the lumbar spine in participants assigned male at birth. This might be due to low estradiol concentrations,” Marianne van der Loos, MD, a researcher in endocrinology at Amsterdam University Medical Centers, told Healio. “Estrogen treatment should be optimized, and lifestyle counseling provided to maximize bone development in individuals assigned male at birth.”
Van der Loos and colleagues conducted a prospective follow-up cohort study of transgender people who started medical transition with a gonadotropin-releasing hormone (GnRH) agonist before the age of 18 years and subsequently used gender-confirming HT for at least 9 years. Clinical data, blood samples and a DXA scan were obtained during a study visit at an outpatient clinic. Retrospective DXA scans were obtained from medical records. Areal BMD and BMD z scores were collected at the femoral neck, lumbar spine and total hip at four time points.
There were 75 transgender people included in the study, of whom 50 were assigned female at birth and 25 were assigned male at birth. Among those assigned male at birth, BMD remained stable during GnRH agonist treatment and then increased during gender-confirming HT. Lumbar spine BMD z score remained stable during HT, leading to a BMD z score decrease of 0.87 points from baseline to follow-up. BMD z scores at the total hip and femoral neck increase during gender-confirming HT and were similar at the end of follow-up compared with pretreatment.
Each 1 kg/m2 increase in BMI was associated with a 0.05-point increase in total hip BMD z score and a 0.08-point increase in femoral neck BMD z score, but no association was found between BMI and BMD z score at the lumbar spine. Researchers also observed a trend toward higher BMD z scores with increased levels of estradiol, but the associations were not significant.
“In future studies, it would be informative to assess the association between estradiol and BMD in a larger study population,” van der Loos said.
Among participants assigned female at birth, BMD z scores decreased during GnRH agonist treatment and then rebounded during gender-confirming HT at all three regions. BMD z scores at the end of follow-up were similar to baseline at the lumbar spine, total hip and femoral neck. At follow-up, each 1 mIU/mL of luteinizing hormone was associated with a 0.03-point decrease in BMD z score at the lumbar spine. Each 1 kg/m2 increase in BMI was associated with a 0.1-point increase in total hip BMD z score and a 0.11-point increase in femoral neck BMD z score. No association was observed between BMI and BMD z score at the lumbar spine.
“The natural course of BMD development in transgender people should be studied, as BMD z scores prior to start of GnRH agonist treatment were already decreased in people assigned male at birth,” van der Loos said. “This would help clarify to what extent the finding that follow-up measurements did not catch up with pretreatment levels at the lumbar spine can be attributed to the hormonal treatment and to what extent to other factors.”
For more information:
Marianne van der Loos, MD, can be reached at m.vanderloos@amsterdamumc.nl.
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