Endocrine Abstracts

Introduction-aim: It has been suggested that estrogen may play an important role in the regulation of endothelium-dependent vasodilatation in both sexes. Especially in men, estradiol administration has been shown to improve endothelial function; however such reports are conflicting. The aim of our study was to examine the relation of endogenous sex hormone levels with markers of early atherosclerosis in a cohort of apparently healthy individuals.

Methods: One hundred and forty-three males (age 46.25±9.56 BMI 20.4 – 43.3, median 26.36 kg/m²) attending a preventive medicine program were examined for unrecognised features of the metabolic syndrome. Early markers of atherosclerosis such as endothelium dependent vasodilatation (flow-mediated-dilatation, FMD) and intima media thickness (IMT) of the common carotid artery were recorded. BMI, waist and hip circumference and arterial pressure were also recorded. Estradiol, testosterone, SHBG, free testosterone, insulin, as well as glucose and lipid levels were measured.

Results: Higher estrogen levels were associated with lower cholesterol levels (r=−0.1963, P=0.047) and higher BMI (r=0.2790, P=0.004). Estradiol levels were positively correlated with FMD (r=0.2016, P=0.041). FMD was negatively associated with total cholesterol (r=−0.2056, P=0.022), low density lipoproteins (r=−0.2322, r=0.009) and triglycerides levels (r=−0.1796, P=0.046). Multivariate analysis showed that the association of estrogen levels with FMD was independent of lipid levels (r=0.292, P=0.041). No significant association of estradiol levels with the IMT of the common carotid artery was found. Free and bioavailable testosterone were negatively associated with the IMT of the left carotid artery only (P<0.03).

Conclusions: Estrogen levels are associated with FMD, showing a protective effect, in apparently healthy, slightly overweight, male subjects. This appears to be a direct effect of endogenous estrogen on cardiovascular health independent of lipid levels. Circulating androgen may be favorable for structural changes such as the IMT thickness of carotid artery.