Bone Mass Effects of Cross-Sex Hormone Therapy in Transgender People: Updated Systematic Review and Meta-Analysis.

Abstract

ContextThe impact of long-term cross-sex hormone therapy (CSHT) in transgender men and women is still uncertain.ObjectiveTo perform a systematic review and meta-analysis and update the evidence regarding the effects of CSHT on bone mineral density (BMD) in transgender men and women.Data SourcesMedline, Cochrane Central Register of Controlled Trials, and Embase were searched for studies published until August 2018.Study SelectionOf 10,849 studies, 19 were selected for systematic review. All included patients were aged >16 years and received CSHT with BMD assessment by dual-energy X-ray absorptiometry (DXA).Data ExtractionData on BMD, CSHT, and clinical factors affecting bone mass were collected. A National Institutes of Health scale was used to assess the quality of studies.Data SynthesisNineteen studies were meta-analyzed (487 trans men and 812 trans women). In trans men, mean BMD difference compared with natal women was not significant in any site in either cross-sectional or before-after studies. In trans women, mean BMD difference was not significant compared with natal men at the femoral neck, total femur, and lumbar spine in cross-sectional studies; before-after studies reported a slight but significant increase in lumbar spine BMD after 12 and ≥24 months of treatment.ConclusionsLong-term CSHT had a neutral effect on BMD in transgender men. In transgender women, only lumbar spine BMD seemed to be affected after CSHT. This evidence is of low to moderate quality as a result of the observational design of studies, small sample sizes, and variations in hormone therapy protocols.