PRIMARY DYSMENORRHOEA AND VASOPRESSIN

Summary

The circulating concentrations of arginine vasopressin on day 1 and on day 5 to 7 of the menstrual cycle were measured by radioimmunoassay in six women with primary dysmenorrhoea and five controls. All women had ovulated in the previous cycle, as indicated by the mid-luteal phase plasma progesterone levels and had normal plasma osmolality and sodium concentrations. The plasma concentrations of progesterone and oestradiol on day 1 of the cycle were also measured, and no significant difference between the two groups was seen. In women with dysmenorrhoea the vasopressin concentration on day 1 was 0.400.038 (SE) μU/ml which was significantly higher than the concentration in normal women on the same day of the cycle 0.20±0.063 (SE) μU/ml (p <0.01). The plasma concentration of vasopressin in normal women on day 5 to 7 was 0.68 0.119 (SE) μU/ml which was significantly higher than on day 1 (p <0.01). A significant difference between day 1 and day 5 to 7 was not seen in dysmenorrheic women, possibly because the values were already elevated on day 1. The results suggest that vasopressin could be a factor of aetiological importance in primary dysmenorrhoea, and also indicate that the vasopressin concentration in plasma can vary according to the day of the menstrual cycle.