Key result
Estrogen therapy linked to improved ICA blood flow, but adding levonorgestrel abolishes the benefit.
Why the study?
Postmenopausal estrogen HRT may improve vascular reactivity via nitric oxide, but concurrent progestin therapy may counteract this effect.
Does long-term estrogen replacement therapy compared to combined hormone replacement therapy improve nitric oxide-dependent vasomotor function in postmenopausal women?
Cohort (n=30)
Does long-term estrogen replacement therapy compared to combined hormone replacement therapy improve nitric oxide-dependent vasomotor function in postmenopausal women?
p-value: p=0.011
Long-term estrogen replacement therapy improves blood flow likely mediated through nitric oxide, an effect that appears to be abolished by the addition of levonorgestrel.
May support estrogen HRT's NO-mediated vascular benefits in small cohorts; leaves open combined HRT effects and clinical relevance.
Postmenopausal hormone replacement therapy (HRT) with estrogen may increase production of the predominant endothelium-derived vasodilator nitric oxide (NO) and consequently improve vascular reactivity. In contrast, concurrent progestin therapy may oppose this beneficial effect. We studied the effect of long-term estrogen HRT and combined HRT on vasomotor function and on plasma nitrate, which reflects the amount of NO in the circulation. As lipid peroxidation affects NO production and impairs endothelial function, we also measured the amount of the in vivo lipid peroxidation marker urinary 8-iso-prostaglandin F(2 alpha). The study group comprised 15 women receiving estradiol valerate HRT (mean age, 56 yr; treatment duration, 10.5 yr) and 15 women receiving combined HRT with estradiol valerate and levonorgestrel (mean age, 58 yr; treatment duration, 11.3 yr). The peak flow velocity (PFV) and pulsatility index of the common carotid and internal carotid artery and the abdominal aorta were measured by ultrasonography after long-term HRT (baseline), after a 4-wk pause and again 3 wk after reintroducing HRT. A statistically significant interaction between the groups and time points was observed in the PFV of the internal carotid artery (P = 0.011). In women taking estradiol valerate, the PFV values decreased significantly after withdrawal of HRT (P = 0.007) and increased again to the baseline level after reintroduction of therapy (P < 0.001). In women receiving combined HRT, the PFV remained stable over all study periods. At baseline, the PFV of women taking estradiol valerate correlated with the plasma nitrate concentration in the common carotid artery (r = 0.646; P = 0.009) and in the abdominal aorta (r = 0.579; P = 0.024). For pulsatility index and urinary 8-iso-prostaglandin F(2 alpha) excretion, there were no significant differences between the groups. Our results suggest that the favorable effects of long-term estrogen treatment on blood flow are at least partly mediated through NO. The addition of levonorgestrel to the treatment regimen appears to abolish this effect.
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Jokela et al. (2003) conducted a cohort in Postmenopausal (n=30). Estradiol valerate HRT vs. Combined HRT with estradiol valerate and levonorgestrel was evaluated on Peak flow velocity (PFV) of the internal carotid artery (p=0.011). Long-term estrogen replacement therapy improved blood flow velocity in the internal carotid artery, an effect that was abolished by the addition of levonorgestrel (P=0.011 for interaction).
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