Vasopressin and atrial natriuretic hormone response to hypertonic saline during the follicular and luteal phases of the menstrual cycle.

Abstract

We studied the hormonal responses to hypertonic saline during the follicular (days 2-9) and luteal (days 21-28) phases of the menstrual cycle in nine healthy young women, aged 19-25 years. On both study days, each woman was infused with 5% hypertonic saline for 1 h at the rate of 0.1 ml/kg/min. Serum progesterone and oestradiol concentrations confirmed the reported stage of the menstrual cycle. No difference in weight or haematocrit was observed between the two stages of the study for each woman. Baseline blood pressure, serum sodium, plasma osmolality, plasma vasopressin and thirst levels were almost identical for both stages, and changed to the same degree during infusion of hypertonic saline. Baseline atrial natriuretic hormone concentrations were higher during the follicular phase and became significantly higher than during the luteal phase following infusion of hypertonic saline. We concluded that the intravascular volume during the luteal phase may be effectively decreased in comparison to the follicular phase.