Sex hormones play an important role in regulating bone formation and maintaining bone mass through both direct bone-level effects and indirect effects, such as changes in body composition. In addition, many other factors play a role such as genetic background, BMI, smoking, alcohol, medication, endocrinological disorders, etc.

Osteoporosis risk in trans people taking oestrogen​​

A recent study showed that trans women already had a lower bone mass and a higher frequency of osteoporosis before the start of hormonal treatment, possibly due to reduced physical activity, less muscle strength and lower vitamin D levels (Van Caenegem et al., 2013). Recent short-term prospective studies show that during hormonal treatment, bone mass is generally maintained and in some cases an increase in bone mass is obtained in trans women (Van Caenegem et al., 2015).

Known risk factors for osteoporosis in trans people taking oestrogen are the use of anti-androgen therapy or GNRH analogues without association of an adequate dose of oestrogens or gonadectomy with the use of inadequate doses of oestrogens.

An increase in lumbar spine bone mineral density has been reported with hormonal treatment in trans AMAB people, with a low rate of fractures (Singh et al., 2017; Wiepjes, et al., 2017).

Osteoporosis risk in trans people taking testosterone

Most studies in trans people taking testosterone show either no change or an increase in bone mineral density during hormonal treatment (Van Caenegem et al., 2015b, Meriggiola et al., 2008; Mueller et al., 2010).

In late-pubertal trans AFAB people menses can be suppressed using a progestational agent, but GnRHa treatment may induce adverse effects on bone mineralisation, amongst others (T’Sjoen et al., 2019).

Although there is also no decrease in bone density to be expected in trans AFAB people taking testosterone (Singh-Ospina et al., 2017), there are very limited data on the risk of osteoporotic fractures (T’Sjoen et al., 2019). Osteoporosis screening should be performed especially in those who stop testosterone treatment after gonadectomy, or in those with limited compliance with therapy or with other risks for bone loss (Hembree at al., 2017).

Screening guidelines

Most experts believe that monitoring bone health and the prevention of osteoporosis in trans persons is important (Van Caenegem & T’Sjoen, 2015; Hembree et al., 2009). Endocrine society guidelines (Hembree et al., 2009) recommend an active assessment of the risk factors for osteoporosis including the (earlier) use of hormonal therapy (with the main risk being the use of anti-androgens or GNRH analogues). Therapy compliance with hormonal treatment is also very important, especially after a gonadectomy. Bone densitometry can be performed based on this risk profile and the intended therapy. It is important to note that parameters vary from bone density tests for cis women and men. Sex assigned at birth as well as which transition-related medical treatments have occured must be taken into account.

References:

  • ​Hembree WC, Cohen-Kettenis P, Delemarre-van de Waal HA, Gooren LJ, Meyer WJ, 3rd, Spack NP, Tangpricha V, Montori VM 2009 Endocrine treatment of transsexual persons: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab 94: 3132-31
  • Meriggiola MC, Armillotta F, Costantino A, Altieri P, Saad F, Kalhorn T, Perrone AM, Ghi T, Pelusi C, Pelusi 2008 Effects of testosterone undecanoate administered alone or in combination with letrozole or dutasteride in female to male transsexuals. J Sex Med 5: 2442–2453
  • Mueller A, Dittrich R, Binder H, Kuehnel W, Maltaris T, Hoffmann I, Beckmann MW 2005 High dose estrogen treatment increases bone mineral density in male-to-female transsexuals receiving gonadotropin-releasing hormone agonist in the absence of testosterone. Eur J Endocrinol 153: 107–13
  • Mueller A, Haeberle L, Zollver H, Claassen T, Kronawitter D, Oppelt PG, Cupisti S, Beckmann MW, Dittrich R 2010 Effects of intramuscular testosterone undecanoate on body composition and bone mineral density in female-to-male transsexuals. J Sex Med 7: 3190–3198
  • Mueller A, Zollver H, Kronawitter D, Oppelt PG, Claassen T, Hoffmann I, Beckmann MW, Dittrich R 2011 Body composition and bone mineral density in male-to-female transsexuals during cross-sex hormone therapy using gonadotrophin-releasing hormone agonist. Exp Clin Endocrinol Diabetes 119: 95–100
  • Singh-Ospina N, Maraka S, Rodriguez-Gutierrez R, et al. Effect of Sex Steroids on the Bone Health of Transgender Individuals: A Systematic Review and Meta-Analysis. J Clin Endocrinol Metab. 2017;102: 3904-13.
  • T’Sjoen G., A. J., de Vries A.L.C., Fisscher, A.D., Nieder T.O., Özer M., Motmans J. (2019). ESSM Position Statement: Assessment and hormonal management in adolescent and adult trans people, with attention for sexual function and satisfaction. Journal of Sexual Medicine.
  • Van Caenegem E, Taes Y, Wierckx K, Vandewalle S, Toye K, Kaufman JM, Schreiner T, Haraldsen I, T’Sjoen G 2013 Low bone mass is prevalent in male-to-female transsexual persons before the start of cross-sex hormonal therapy and gonadectomy. Bone 5: 492-497
  • Van Caenegem E, Wierckx K, Taes Y, Schreiner T, Vandewalle S, Toye K, Kaufman JM, T’Sjoen G 2015 Preservation of volumetric bone density and geometry in trans women during cross-sex hormonal therapy: a prospective observational study. Osteoporos Int. 2; 26 (1): 35-47
  • Van Caenegem E, Wierckx K, Taes Y, Schreiner T, Vandewalle S, Toye K, Lapauw B, Kaufman JM, T’Sjoen G 2015 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). Eur J Endocrinol 172 (2): 163-71
  • Van Caenegem E, TʼSjoen G 2015 Bone in trans persons. Curr Opin Endocrinol Diabetes Obes: 22 (6): 459-66
  • Wiepjes, C. M., Vlot, M. C., Klaver, M., Nota, N. M., de Blok, C. J., de Jongh, R. T., . . . den Heijer, M. (2017). Bone Mineral Density Increases in Trans Persons After 1 Year of Hormonal Treatment: A Multicenter Prospective Observational Study. Journal of Bone and Mineral Research, 32(6), 1252-1260. doi:10.1002/jbmr.3102