Vasopressin and prostaglandins in premenstrual pain and primary dysmenorrhea.

Both vasopressin and PGF2 alpha are effective uterine stimulants in the non-pregnant human uterus, especially around the onset of menstruation. In order to clarify the relationship of these hormones to menstrual pain, plasma concentrations of vasopressin and two prostaglandin metabolites (15-keto-13,14-dihydro-PGF2 alpha and 11-ketotetranor PGF metabolites) were measured in serial blood samples taken premenstrually and during menstruation. Five women with premenstrual pain gave 7-9 blood samples at intervals of 30 minutes on the day preceding the onset of menstruation. From 5 women with severe primary dysmenorrhea a corresponding series of blood samples were taken during the first day of menstruation. Two groups of 5 women with no symptoms served as controls, either premenstrually or during menstruation. In the women with premenstrual pain the vasopressin concentrations were significantly higher than in the corresponding control group. Even higher and markedly fluctuating vasopressin levels were found in the women with dysmenorrhea who, in general, had more intense pain than the women with premenstrual symptoms. In the group with dysmenorrhea there was also a significant rise in plasma concentration of the PG metabolites. No such increase was seen in the group with premenstrual pain. It is concluded that the pathophysiology of premenstrual pain could imply increased vasopressin secretion. The more severe pain in primary dysmenorrhea seems to be the result of a combined effect of vasopressin and PGF2 alpha.