Sex differences in the urinary catecholamines.

Urinary excretion of dopamine, norepinephrine and epinephrine was measured in a group of adult men and women of comparable age during recumbency and then during stimulation by upright posture. Urinary norepinephrine was found to be significantly higher in women (30.3 +/- 4.4 ng/min/m2 B.S.) than in men (18.3 +/- 2.7 ng/min/m2 B.S.) during recumbency; there was no significant sex difference in dopamine and epinephrine excretion. There was no apparent trend indicating a difference in urinary catecholamine excretion during the follicular or luteal phase of the menstrual cycle. In response to upright posture, there was a significant decrease in the urinary dopamine-norepinephrine ratio in both sexes; the magnitude of the decrease was, however, significantly higher in men (-9.9 +/- 3.0) than in women (-2.05 +/- 0.72). The mechanisms of the sex differences in urinary catecholamine excretion are unknown. Clinical studies involving catecholamines have to take these sex differences into account.