Urinary excretion of vasoactive markers following estrogen replacement therapy in postmenopausal women

The effect of estradiol on the renal excretion of vasoactive substances was studied in postmenopausal women. The following markers surrogating an estrogenic effect on the cardiovascular system were measured: prostacyclin and thromboxane, cGMP, which reflects systemic nitric monoxide production, serotonin and relaxin.

The effect of estradiol was compared using two clinical forms of administration, transdermal and oral, in two groups of 20 postmenopausal women each. The treatment was carried out for two and four weeks, respectively. Nocturnal urine was collected over 8 hours before and after estradiol treatment. The quantity of markers excreted during the experiment was determined.

Excretion of prostacyclin and thromboxane, calculated as prostacyclin/thromboxane ratio, was increased using both forms of administration. Both forms of treatment brought about only slight non-significant changes in renal cGMP excretion compared with values before treatment. The production of serotonin and relaxin was only increased using transdermal treatment.

The resulting data show that estradiol replacement in postmenopausal women is able to increase renal excretion of various vasoactive substances implying a vasodilative effect of estrogen. This was seen, both in transdermal and oral administration, transdermal application having a more pronounced effect on the markers than oral administration.