Effects of hormone replacement therapy on plasma viscosity and Doppler variations in postmenopausal non-smokers and heavy smokers

Objectives. To evaluate the effects of transdermal hormone replacement therapy (HRT) on some biological cardiovascular risk factors, specifically thromboxane B-2 level and plasma viscosity. Furthermore, we investigated Doppler flow modifications at the level of the uterine, internal carotid, ophthalmic and bladder wall arteries, and evaluated whether there were significant differences, in the examined parameters, between postmenopausal women who were non-smokers and heavy smokers. Methods. Forty-three postmenopausal women (age 53.6 +/- 3.3 years, mean +/- standard deviation) participated in the study and were divided into two groups (Group I: n = 21, normal controls; and Group II: n = 22, heavy smokers). Patients were treated with continuous estradiol transdermal supplementation and 12-day courses of medroxyprogesterone acetate every 2 months. They were studied at baseline and after 6 months (in the estrogen-only phase of the cycle). Results. Results showed a beneficial effect of hormone substitution after 6 months of therapy. Plasma viscosity decreased significantly after 6 months of therapy both in non-smokers and heavy smokers (-18% and -14%, respectively). Plasma levels of thromboxane 132, which were similar at baseline, underwent a dramatic reduction in both Group I and Group II (-93% and -88%, respectively). Doppler assessment of pulsatility index at the level of the uterine, internal carotid, ophthalmic and bladder wall arteries showed a significant reduction in vascular impedance at the end of treatment in both groups. However, the treatment was significantly less beneficial, in terms of the analyzed factors, in heavy smokers. Conclusions. Cigarette smoking represents a cardiovascular risk factor that can only partially be modified by the administration of transdermal HRT.