Association between serum testosterone and measures of cardiovascular health among transgender individuals using gender-affirming testosterone therapy: a cross-sectional study.

Background: Gender-affirming testosterone therapy (GATT) use may be associated with increased systolic blood pressure (SBP). The association between serum testosterone and cardiovascular health in individuals using GATT is unknown. The objective of this study was to estimate the association between serum testosterone and validated measures of cardiovascular health, including SBP and arterial stiffness, in persons assigned female sex at birth using GATT.

Methods: Healthy participants assigned female sex at birth on a stable GATT regimen for ≥ 4 months were recruited to this community-partnered exploratory cross-sectional study. Exposures of interest were total and free serum testosterone concentration. As our primary outcome, SBP was measured by an automated sphygmomanometer, and carotid-radial pulse wave velocity (PWVcr) and aortic augmentation index (AIx) were used to measure arterial stiffness via applanation tonometry.

Results: Participants (n = 18, median age 28 years, range: 18, 50) who predominantly self-identified as white (94%) and had been using GATT for a median of 48 months (range: 5, 84) were studied. Resting SBP, PWVcr, and AIx were 113 mmHg (range: 102, 129), 7 m/s (range: 4, 9), and 9% (range: - 10, 23), respectively. Total and free serum testosterone were not significantly associated with SBP or PWVcr. Free, but not total, serum testosterone was positively associated with AIx (p = 0.03). Sensitivity analyses did not modify any results.

Conclusions: In healthy transgender individuals, serum testosterone concentrations may not be associated with measures of cardiovascular health. However, these results need to be interpreted with caution given the limited sample size.