Persistent vaginal bleeding during gender-affirming hormone therapy in transgender men.

Purpose: While it is common for menstrual cycles to cease within the initial 6 months of treatment, there are instances where some transgender men may not experience this cessation. We analyzed transgender men undergoing gender-affirming hormone therapy (GAHT) with testosterone who experienced breakthrough bleeding in order to identify the factors associated with this condition.

Methods: In this case-control study, 24 transgender men in the case group and 48 in the control group were assessed for clinical, sociodemographic, hormonal, and body composition variables using dual-energy X-ray absorptiometry. All participants had been on GATH for at least 6 months.

Results: A few transgender men experienced persistent breakthrough bleeding, which was associated with decreased testosterone levels and free androgen index (FAI) compared with controls (p = 0.002 and p = 0.008, respectively). Among individuals with breakthrough bleeding, 50% had testosterone levels below the lowest tertile calculated for the sample, compared with 18.8% on controls (p = 0.007). After therapy adjustment, testosterone levels increased compared with the values obtained in the initial bleeding episode (p = 0.031). Eight transgender men required the addition of an oral progestogen to achieve amenorrhea, and these individuals had higher BMI than those in whom the adjustment of the parenteral testosterone dose was adequate (p = 0.026). A univariate prevalence ratio analysis revealed a negative association of persistent bleeding with testosterone levels (p = 0.028) and FAI levels (p = 0.019).

Conclusion: Higher BMI and lower levels of testosterone and FAI were the main factors associated with breakthrough bleeding in transgender men.