The association of gender-affirming hormone therapy duration and body mass index on bone mineral density in gender diverse adults

Sean J Iwamoto; John D Rice; Kerrie L Moreau; Marc-André Cornier; Margaret E Wierman; Mary P Mancuso; Amanuail Gebregzabheir; Daniel B Hammond; Micol S Rothman

doi:10.1016/j.jcte.2024.100348

The association of gender-affirming hormone therapy duration and body mass index on bone mineral density in gender diverse adults

J Clin Transl Endocrinol. 2024 Apr 30:36:100348. doi: 10.1016/j.jcte.2024.100348. eCollection 2024 Jun.

Authors

Sean J Iwamoto^{1

2

3}, John D Rice⁴, Kerrie L Moreau^{5

6}, Marc-André Cornier⁷, Margaret E Wierman^{1

2}, Mary P Mancuso⁸, Amanuail Gebregzabheir¹, Daniel B Hammond^{1

3}, Micol S Rothman^{1

3}

Affiliations

¹ Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado School of Medicine, University of Colorado Anschutz Medical Campus, 12801 E 17th Ave, 7103, Aurora, CO 80045, USA.
² Endocrinology, Medicine and Research Services, Rocky Mountain Regional VA Medical Center, 1700 N Wheeling St, 111H, Aurora, CO 80045, USA.
³ UCHealth Integrated Transgender Program, University of Colorado Hospital, 1635 Aurora Court, Anschutz Outpatient Pavilion, 6th floor, Aurora, CO 80045, USA.
⁴ Department of Biostatistics, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
⁵ Division of Geriatrics, Department of Medicine, University of Colorado School of Medicine, University of Colorado Anschutz Medical Campus, 12631 E 17th Ave, 8111, Aurora, CO 80045, USA.
⁶ Geriatric Research Education and Clinical Center, VA Eastern Colorado Healthcare System, Rocky Mountain Regional VA Medical Center, 1700 N Wheeling St, Aurora, CO 80045, USA.
⁷ Division of Endocrinology, Diabetes and Metabolic Diseases, Department of Medicine, Medical University of South Carolina, 96 Jonathan Lucas St, CSB 822, Charleston, SC 29425, USA.
⁸ Division of General Internal Medicine, Department of Medicine, University of Colorado School of Medicine, University of Colorado Anschutz Medical Campus, 12631 E 17th Ave, Aurora, CO, 80045, USA.

Abstract

Introduction: Feminizing and masculinizing gender-affirming hormone therapy (fGAHT, mGAHT) results in bone mineral density (BMD) maintenance or improvement over time in transgender and gender diverse (TGD) adults. Mostly European TGD studies have explored GAHT's impact on BMD, but the association of BMI and BMD in TGD adults deserves further study.

Objective: To determine whether GAHT duration or BMI are associated with BMD and Z-scores among TGD young adults.

Methods: Cross-sectional study of nonsmoking TGD adults aged 18-40 years without prior gonadectomy or gonadotropin-releasing hormone agonist (GnRHa) therapy taking GAHT for > 1 year. BMD and Z-scores were collected from dual-energy x-ray absorptiometry. Associations between femoral neck, total hip, and lumbar spine BMDs and Z-scores and the predictors, GAHT duration and BMI, were estimated using linear regression.

Results: Among 15 fGAHT and 15 mGAHT, mean BMIs were 27.6 +/- standard deviation (SD) 6.4 kg/m² and 25.3 +/- 5.9 kg/m², respectively. Both groups had mean BMDs and Z-scores within expected male and female reference ranges at all three sites. Higher BMI among mGAHT was associated with higher femoral neck and total hip BMDs (femoral neck: β = 0.019 +/- standard error [SE] 0.007 g/cm², total hip: β = 0.017 +/- 0.006 g/cm²; both p < 0.05) and Z-scores using male and female references. GAHT duration was not associated with BMDs or Z-scores for either group.

Conclusions: Z-scores in young, nonsmoking TGD adults taking GAHT for > 1 year, without prior gonadectomy or GnRHa, and with mean BMIs in the overweight range, were reassuringly within the expected ranges for age based on male and female references. Higher BMI, but not longer GAHT duration, was associated with higher femoral neck and total hip BMDs and Z-scores among mGAHT. Larger, prospective studies are needed to understand how body composition changes, normal or low BMIs, and gonadectomy affect bone density in TGD adults.

Keywords: Body mass index; Bone mineral density; Gender-affirming hormone therapy; Hip; Lumbar spine; Transgender.