Urinary elimination of oxytocin and vasopressin measured by radioimmunoassay in different phases of the menstrual cycle in women

: Urinary arginine-vasopressin (AVP) and oxytocin (OT) excretion were measured by radioimmunoassay and studied in 3 normally cycling women. No difference for AVP and OT excretion was found between the different phases of the menstrual cycle. But in one subject with a typical pre-menstrual syndrom (weight gain of 1.5 kg), a significant statistical difference was found in AVP excretion (p less than 0.05) between the pre-ovulatory (25.3 +/- 3.08 ng/24 h) and the post-ovulatory (39.45 +/- 5.59 ng/24 h) phase. The well known stimulatory effect of estrogen as judged from plasma studies on neurohypophyseal hormones was thus difficult to demonstrate in urine. These results could be explained by the fact that the kidney destroys both AVP and OT, but OT at a higher rate than AVP.