Reproductive hormones in plasma over the menstrual cycle in primary dysmenorrhea compared with healthy subjects.

The pathogenesis of primary dysmenorrhea is still poorly understood. The objective of the present investigation was to study differences in plasma concentrations of reproductive hormones in women with primary dysmenorrhea vs. healthy controls. In a prospective, parallel-group study we determined the plasma concentrations of oxytocin, vasopressin, follicle-stimulating hormone (FSH), luteinizing hormone (LH), 17beta-estradiol (17beta-E2), progesterone and prostaglandin F 2alpha metabolite (15-keto-13,14-dihydro-PGF 2alpha) over one menstrual cycle in eight women with primary dysmenorrhea and eight healthy volunteers. In dysmenorrheic women the plasma concentration of oxytocin was significantly higher at menstruation (p = 0.0084) and that of vasopressin significantly lower at ovulation (p = 0.0281) compared with healthy women. They had also higher FSH levels in the early follicular phase (p = 0.0087) and at menstruation (p = 0.0066) and the 17beta-E2 concentration was higher in the late follicular phase (p = 0.0449). No differences were seen for LH, progesterone and PGF 2alpha metabolite. The differences of oxytocin, vasopressin, FSH and 17beta-E2 concentrations found in plasma suggest an involvement of these hormones in mechanisms of primary dysmenorrhea. These mechanisms seem to be mainly regulated through the hypothalamus and pituitary. The influence of oxytocin on the non-pregnant uterus seems to be more important than earlier believed.