Compromised endothelial function in transgender men taking testosterone.

Context: Transgender men (TGM) are persons assigned female gender at birth with a male gender identity and are routinely treated with testosterone. Androgen excess is associated with endothelial dysfunction among cisgender females (CGF) and is an early sign of atherosclerosis and hypertension.

Objective: To determine the effect of testosterone treatment on endothelial function in TGM.

Setting: The John B. Pierce Laboratory and Yale School of Medicine.

Subjects: Eleven TGM (age 27 ± 5 years; BMI 24.4 ± 3.7 kg/m ) receiving testosterone (T) and 20 CGF (28 ± 5 years; BMI 26.0 ± 5.1 kg/m ) during the early follicular phase of their menstrual cycle.

Design And Outcome Measures: We evaluated brachial vasodilatory responses following stimuli designed to elicit shear stress using 5-minute occlusion to determine endothelial function (flow-mediated vasodilation, FMD).

Results: Total T was greater in the TGM compared to CGF (484.6 ± 122.5 vs 1.5 ± 0.7 ng/dL), as was free T (83.9 ± 32.4 vs 1.9 ± 0.8 pg/dL). FMD was markedly lower in the TGM (4.5 ± 2.7%) compared to the CGF (8.1 ± 2.9%, P = .002) indicating significantly diminished endothelial function in TGM.

Conclusions: We have shown for the first time that in TGM the androgen-dominant hormonal milieu was associated with impaired endothelial function. Endothelial dysfunction precedes clinically detectable atherosclerotic plaque in the coronary arteries, so is an important marker for clinical cardiovascular risk. Therefore, attention to cardiovascular risk factors should be integral to the care of transgender men.