Abstract 4185: Low Testosterone Level is an Independent Determinant of Endothelial Dysfunction in Men
Background: Epidemiological studies have shown that relative hypogonadism is associated with the higher incidence of cardiovascular disease, the mechanism of which remains unknown. We investigated whether relative hypogonadism would be related to endothelial dysfunction in men.
Methods: Consecutive 188 men (mean age ± SD = 47±15 years), who examined flow-mediated vasodilation (FMD) of the brachial artery using ultrasonography, were enrolled. The subjects with cardiovascular disease, malignancy, overt endocrine disease or having steroid hormones were excluded. Plasma hormone levels were determined after 12-hour fast in the morning, and the relationship between hormone levels and FMD was analyzed.
Results: Total and free testosterone and dehydroepiandrosterone-sulfate (DHEA-S) were significantly correlated with %FMD (r=0.262, 0.355 and 0.296, respectively; p<0.001), while estradiol or cortisol was not. %FMD in the highest quartile of free testosterone was 1.7-fold higher than that in the lowest quartile (5.6±2.9 vs. 3.3±2.6 [mean±SD], p<0.05). Multiple regression analysis revealed that total and free testosterone were related to %FMD independent of age, body mass index, hypertension, hypercholesterolemia, diabetes mellitus and smoking (β=0.197 and 0.240, respectively; p<0.01), and independent of age, body mass index, systolic blood pressure, total cholesterol, HDL cholesterol, fasting plasma glucose, smoking and carotid intima-media thickness (β=0.211 and 0.259, respectively; p<0.01). DHEA-S was not significantly related to %FMD on multivariate analysis.
Conclusions: Low plasma testosterone level was associated with endothelial dysfunction in men independent of other risk factors, suggesting a protective effect of testosterone on the endothelium.