Body composition, bone turnover, and bone mass in trans men during testosterone treatment: 1-year follow-up data from a prospective case-controlled study (ENIGI)
Abstract
PURPOSE: To assess the evolution of body composition and bone metabolism in trans men during the first year of cross-sex hormonal therapy. METHODS: In a prospective controlled study, we included 23 trans men (female-to-male trans persons) and 23 age-matched control women. In both groups, we examined grip strength (hand dynamometer), biochemical markers of bone turnover (C-terminal telopeptides of type 1 collagen (CTX) and procollagen 1 aminoterminal propeptide (P1NP)), total body fat and lean mass, and areal bone mineral density (aBMD) by dual-X-ray absorptiometry (DXA) and fat and muscle area at the forearm and calf, bone geometry, and volumetric bone mineral density (vBMD) by peripheral quantitative computed tomography (pQCT), before treatment and after 1 year of treatment with undecanoate (1000 mg i.m./12 weeks). RESULTS: Before hormonal treatment, trans men had similar bone and body composition compared with control women. Testosterone treatment induced in trans men a gain in muscle mass (+10.4%) and strength and loss of fat mass (-9.7%) (all P<0.001) and increased the levels of P1NP and CTX (both P<0.01). Areal and volumetric bone parameters remained largely unchanged apart from a small increase in trabecular vBMD at the distal radius and in BMD at the total hip in trans men (P=0.036 and P=0.001 respectively). None of these changes were observed in the control group. CONCLUSIONS: Short-term testosterone treatment in trans men increased muscle mass and bone turnover. The latter may rather reflect an anabolic effect of testosterone treatment rather than bone loss.
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Transgender women retained a hand-grip strength advantage after 2 years of 23% over female baseline measurements.
“Comparison with data in a separately-published, parallel cohort of transgender men [76] demonstrated a retained hand-grip strength advantage after 2 years of 23% over female baseline measurements”
From Transgender Women in the Female Category of Sport: Perspectives on Testosterone Suppression and Performance Advantage (2021) · cites this paper as [76]
In 23 transmen administered adult male testosterone doses, total body muscle size and limb muscle size increased by 6.5% to 16.6% and grip strength by 18% compared with age-matched untreated control women.
“In a second study, 23 transmen administered adult male testosterone doses also produced striking increases in total body muscle size and limb muscle size (by 6.5% to 16.6%) and grip strength (by 18%) compared with age-matched untreated control women (115).”
From Circulating Testosterone as the Hormonal Basis of Sex Differences in Athletic Performance (2018) · cites this paper as [115]
Two prospective studies of the first 12 months of testosterone treatment in transmen show a consistent major increase in muscle mass and strength due to testosterone administration.
“Similarly, two prospective studies of the first 12 months of treatment of transmen [female-to-male (F2M) transgender] shows a consistent major increase in muscle mass and strength due to testosterone administration.”
From Circulating Testosterone as the Hormonal Basis of Sex Differences in Athletic Performance (2018) · cites this paper as [115]
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References 50 · Cited by 160
- Authors
- Van Caenegem, E., Wierckx, K., Taes, Y., Schreiner, T., Vandewalle, S., Toye, K., Lapauw, B., Kaufman, J.-M., & T'Sjoen, G.
- Affiliations
- Oslo University Hospital (NO)
- Venue
- European Journal of Endocrinology
- Publisher
- Oxford University Press (OUP)
- Published
- 2015-02
- Volume
- 172
- Issue
- 2
- Pages
- 163-171
- ISSN
- 0804-4643 (ISSN-L)
- 1479-683X
- OpenAlex
- W2048984588
- Cited by
- 160
- References
- 50
- Citations by year
- 2026: 11 · 2025: 13 · 2024: 16 · 2023: 11 · 2022: 24 · 2021: 15 · 2020: 18 · 2019: 19 · 2018: 10 · 2017: 10 · 2016: 11 · 2015: 2
- FWCI
- 7.94
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- European Journal of Endocrinology (publishedVersion)
- PubMed (publishedVersion)
- Ghent University Academic Bibliography (Ghent University) (submittedVersion)
- Topics
- Health Sciences › Medicine › Orthopedics and Sports Medicine › Bone health and osteoporosis research
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Hormonal and reproductive studies
- Social Sciences › Psychology › Social Psychology › LGBTQ Health, Identity, and Policy
- Keywords
- transgender men, testosterone replacement therapy, body composition, bone turnover, bone mineral density, muscle mass, fat mass, grip strength, bone geometry, trabecular bone, female-to-male transgender people
- MeSH terms
- Adolescent, Adult, Body Composition, Female, Follow-Up Studies, Humans, Male, Middle Aged, Prospective Studies, Testosterone, Bone Density, Case-Control Studies, Bone Remodeling, Treatment Outcome, Muscle Strength, Young Adult, Transgender Persons
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