The Effects of Testosterone on Bone Turnover Markers Among Hormone-Naive Transgender Men

Purpose: Transgender medicine has become rapidly recognized and evolving in health care system. The consequences of hormone therapy are among the most concerned health issues in transgender population. This study aims to compare bone turnover markers before and after testosterone administration in hormone-naive transgender men. Methods: This prospective study included 20 hormone-naive transgender men. Comparisons of serum C-terminal cross-linking telopeptide of type I collagen (CTX) at baseline with 12 weeks and 24 weeks were analyzed using Wilcoxon signed-rank test. Serum procollagen type I N-propeptide (P1NP) and osteocalcin levels at 24 weeks compared to baseline were also assessed. Pearson's correlation coefficient analysis was used to compare the correlation between serum bone turnover markers and sex hormone levels. Results: At 12 weeks after testosterone administration, significant higher serum CTX level compared to baseline (p-value 0.035) was demonstrated. At 24 weeks after testosterone administration, there were significant differences in serum CTX, P1NP, and osteocalcin levels compared to baseline (p-value 0.019, <0.001, and 0.003, respectively). Serum CTX, P1NP, and osteocalcin levels significantly increased 28.30%, 44.26%, and 21.89%, respectively, at 24 weeks after testosterone treatment. There was a moderate negative correlation between serum CTX and estradiol level. Conclusion: Testosterone administration in transgender men significantly increased the levels of bone turnover markers. Further, well-controlled studies of bone health in transgender men are required to prove and assess the other aspects of bone status over a long-term follow-up period. Thai Clinical Trial Registry identification number TCTR20220817002.