Effects of dydrogesterone on hydroelectrolytic metabolism: a randomized double-blind study

To determine a possible influence on sodium balance or blood pressure of a normal treatment with dydrogesterone, a randomized cross-over double-blind study was performed on 22 healthy young women. Each woman had (in random order) 1 cycle of treatment with dydrogesterone (20 mg/day during the last 12 days of the menstrual cycle) and 1 with equivalent placebo. On days 15 and 27 of each cycle the following data were noted: weight, systolic (SBP) and diastolic (DBP) blood pressures (mean of 13 measurements during 1 hour), natriuresis, kaliuresis, plasma renin activity (PRA) and plasma aldosterone concentration (P ald). For each variable the difference between day 27 and day 15 was calculated. The comparison between progesterone and placebo influence was made on these differences. Neither for sodium balance nor for blood pressure were there any statistically significant differences between placebo and dydrogesterone. However, the confidence intervals of the difference were rather large. There is a need for a more extensive study to confirm the absence of influence of progesterone on sodium balance and blood pressure.