Sex hormones and carotid atherosclerosis in the metabolic syndrome.

Sex Hormones and Carotid Atherosclerosis in the Metabolic Syndrome To the Editor: We read with great interest the recent article by Dr Iglseder et al1 dealing with sex differences in early carotid atherosclerosis in the metabolic syndrome. The results of their study demonstrated that extent of plaques and cariotid artery intima-media thickness parameters were significantly higher in subjects with the metabolic syndrome. In addition, it was demonstrated that in women, blood glucose and triglyceride levels showed the strongest association with intima-media thickness of the carotid artery, whereas in men high-density lipoprotein ranked first. The authors proposed that the effect of the metabolic syndrome on early atherosclerosis is more pronounced in women, and that the impact of the components of the metabolic syndrome on the carotid artery injury differs between men and women. Evidence indicates that vascular endothelial function is markedly influenced by estrogen and is improved by hormone replacement therapy in postmenopausal women.2 In an in vitro study presented earlier, we demonstrated that 17 -estradiol increased membrane fluidity (a reciprocal value of membrane microviscosity) of erythrocytes and improved the rigidity of cell membranes in postmenopausal women via a nitric oxide– and cGMP-dependent mechanism.3 In a separate series of experiments, we showed that hormone replacement therapy restored the membrane microviscosity in elderly women with a concomitant increase in plasma nitric oxide metabolite level.4 These findings suggest that because abnormalities in membrane microviscosity could cause a disturbance in the rheological behavior and the microcirculation, estrogen deficiency might be involved in the pathogenesis of vascular complications in elderly women. Recently, the role of estrogen in male physiology has also become evident, and normal physiological estrogen, which is converted from testosterone by aromatase, may confer cardiovascular benefits for elderly men.5 In this context, we speculate that changes in sex hormones might modify the course of cardiovascular diseases in both men and women. Iemolo et al6 demonstrated that women had greater carotid artery stenosis compared with men. Although the authors described that the majority of women in the population were in the postmenopausal state, we would like to know the endogenous sex hormone status in both men and women in the present study. Because insulin resistance might be strongly linked to estrogen concentration,7 further studies should be performed to assess more precisely the relationship between sex hormones and vascular complications in the metabolic syndrome.