[Effect of transdermal versus oral estradiol administration on the excretion of vasoactive markers in postmenopausal women]. / Wirkung von transdermaler oder oraler Ostradiolgabe auf die Ausscheidung vasoaktiver Mediatoren bei postmenopausalen Frauen.

ABSTRACT

OBJECTIVES: Can transdermal (n=20) and oral (n=20) estradiol substitution influence the urinary excretion of vasoactive substances in postmenopausal women? METHOD: The vasoactive substances prostacyclin and thromboxane, cyclic guanosine monophosphate, which can reflect the systemic NO production, serotonin, relaxin, insulin and melatonin were measured in nocturnal 8-hour urine before and after 2 and 4 weeks' estradiol treatment. RESULTS: The excretion ot prostacyclin and thromboxane, calculated as a prostacyclin/thromboxane quotient, was shifted towards higher prostacyclin production. Only minor changes could be registered for the cyclic guanosine monophosphate excretion. The production of serotonin, relaxin and insulin was increased only after transdermal treatment with estradiol. For melatonin no changes could be observed. CONCLUSIONS: Hormone substitution therapy with estradiol in postmenopausal women is able to increase the urinary excretion of various vasoactive substances, both after transdermal and oral application, indicating a vasodilatory estrogenic action. Transdermal administration was more effective, although lower dosages were applied. An explanation may be that transdermal estradiol elicits continuous and constant effects on estrogenic target organs.