Proandrogenic and antiandrogenic progestins in transgender youth: differential effects on body composition and bone metabolism
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Context: Progestins can be used to attenuate endogenous hormonal effects in late-pubertal transgender (trans) adolescents (Tanner stage B4/5 and G4/5). Currently, no data are available on the effects of progestins on the development of bone mass or body composition in trans youth. Objective: To study prospectively the evolution of body composition and bone mass in late-pubertal trans adolescents using the proandrogenic or antiandrogenic progestins lynestrenol (L) and cyproterone acetate (CA), respectively. Design and Outcome Measurements: Forty-four trans boys (Tanner B4/5) and 21 trans girls (Tanner G4/5) were treated with L or CA for 11.6 (4 to 40) and 10.6 (5 to 31) months, respectively. Anthropometry, grip strength, body composition, and bone mass, size, and density were determined by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography before the start of progestin and before addition of cross-sex hormones. Results: Using L, lean mass [+3.2 kg (8.6%)] and grip strength [+3 kg (10.6%)] significantly increased, which coincided with a more masculine body shape in trans boys. Trans girls showed loss of lean mass [-2.2 kg (4.7%)], gain of fat mass [+1.5 kg (9.4%)], and decreased grip strength Z scores. CA limited normal bone expansion and impeded pubertal bone mass accrual, mostly at the lumbar spine [Z score: -0.765 to -1.145 (P = 0.002)]. L did not affect physiological bone development. Conclusion: Proandrogenic and antiandrogenic progestins induce body composition changes in line with the desired appearance within 1 year of treatment. Bone health, especially at the lumbar spine, is of concern in trans girls, as bone mass accrual is severely affected by androgen suppressive therapy.
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One study of adolescent participants who only reached a final testosterone level of 8.8 nmol/L exhibited forearm and calf cross-sectional area decreases of 4.1% and 8.9%, respectively.
“One of these studies40 examined adolescent participants who only reached a final testosterone level of 8.8 nmol/L and exhibited forearm and calf CSA decreases of 4.1% and 8.9%, respectively.”
From How does hormone transition in transgender women change body composition, muscle strength and haemoglobin? Systematic review with a focus on the implications for sport participation (2021) · cites this paper as [40]
The Body composition and grip strength section reports decreased forearm and lower-leg muscle area in adolescent trans girls. Table 2 gives their final mean testosterone as 253.35 ng/dL, approximately 8.8 nmol/L. Our copy does not report the claimed 4.1% and 8.9% decreases, so those magnitudes cannot be verified. (LLM, conf=0.86)
Experimental — accuracy not yet measuredA decrease in muscle cross-sectional area of 1.5%-11.7% was reported over periods ranging from 12 to 36 months in transwomen on GAHT.
“A decrease in CSA of 1.5%–11.7% was reported over periods ranging from 12 to 36 months.”
From How does hormone transition in transgender women change body composition, muscle strength and haemoglobin? Systematic review with a focus on the implications for sport participation (2021) · cites this paper as [40]
The Body composition and grip strength section (page not available) reports decreased forearm and lower-leg muscle area in trans girls treated with cyproterone acetate, but does not give the claimed 1.5%–11.7% range. The Results give a mean interval of 10.57 months between examinations for trans girls, not a 12–36-month observation period. Participants and treatments says measurements were taken before addition of cross-sex hormones, so the reported decrease was not observed during GAHT as the claim suggests. (LLM, conf=0.90)
Experimental — accuracy not yet measuredTwo ENIGI studies found no significant strength differences, although one of these studies was carried out on adolescents who failed to reach typical female testosterone levels (8.8 nmol/L after GAHT).
“Two ENIGI studies37 40 found no significant strength differences, although one of these studies40 was carried out on adolescents who failed to reach typical female testosterone levels (8.8 nmol/L after GAHT).”
From How does hormone transition in transgender women change body composition, muscle strength and haemoglobin? Systematic review with a focus on the implications for sport participation (2021) · cites this paper as [40]
The Body composition and grip strength section reports no significant change in grip strength among trans girls during the study, but it does not report no strength differences between groups. Table 2 reports mean total testosterone of 253.35 ng/dL after cyproterone acetate treatment in trans girls, approximately 8.8 nmol/L. The paper describes this as progestin treatment, not GAHT. (LLM, conf=0.85)
Experimental — accuracy not yet measuredAlthough the transwomen in most of the studies achieved testosterone levels within the reference range for cisgender women, there were five studies in which the transfemales had post-GAHT testosterone values greater than 5 nmol/L.
“Although the transwomen in most of the studies achieved testosterone levels within the reference range for cisgender women, there were five studies38 40 47 49 51 in which the transfemales had post-GAHT testosterone values greater than 5 nmol/L.”
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References 41 · Cited by 63
- Authors
- Tack, L. J. W., Craen, M., Lapauw, B., Goemaere, S., Toye, K., Kaufman, J.-M., Vandewalle, S., T’Sjoen, G., Zmierczak, H.-G., & Cools, M.
- Affiliations
- Ghent University Hospital (BE)
- Department of Endocrinology, Ghent University Hospital, Ghent University, Ghent, Belgium
- Corresponding author
- Cools, Martine
- Venue
- The Journal of Clinical Endocrinology & Metabolism
- Publisher
- The Endocrine Society
- Published
- 2018-04-16
- Volume
- 103
- Issue
- 6
- Pages
- 2147-2156
- ISSN
- 0021-972X (ISSN-L)
- 1945-7197
- OpenAlex
- W2801313327
- Cited by
- 63
- References
- 41
- Citations by year
- 2026: 4 · 2025: 11 · 2024: 14 · 2023: 8 · 2022: 7 · 2021: 4 · 2020: 11 · 2019: 4
- FWCI
- 6.45
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- The Journal of Clinical Endocrinology & Metabolism (publishedVersion)
- PubMed (publishedVersion)
- Ghent University Academic Bibliography (Ghent University) (submittedVersion)
- Topics
- Social Sciences › Psychology › Social Psychology › LGBTQ Health, Identity, and Policy
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Hormonal and reproductive studies
- Health Sciences › Medicine › Orthopedics and Sports Medicine › Bone health and osteoporosis research
- Keywords
- progestins, transgender youth, lynestrenol, cyproterone acetate, body composition, bone accrual, bone metabolism, lean body mass, fat mass, grip strength, androgen deprivation therapy, puberty
- MeSH terms
- Adolescent, Body Composition, Bone Development, Child, Estradiol, Female, Follicle Stimulating Hormone, Humans, Luteinizing Hormone, Lumbar Vertebrae, Lynestrenol, Male, Progestins, Sex Hormone-Binding Globulin, Testosterone, Transsexualism, Absorptiometry, Photon, Bone Density, Treatment Outcome, Cyproterone Acetate, Hand Strength, Transgender Persons
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