Renal function, plasma sodium and osmolality during the menstrual cycle

ABSTRACT

In order to assess whether hormonal changes occurring during the menstrual cycle affect function, glomerular filtration rate (C cr), and proximal tubular reabsorption of sodium and water (lithium clearance; C li) were assessed in 9 healthy women in 2 phases of the menstrual cycle. Plasmar sodium and osmolality were also measured. Each subject was studied three time ("basal", "proliferative" and "luteal" phases), point on her customary sodium intake, and in a controlled (sitting) posture. There were no significance differences between the phases with respect to any of the renal variables studied. There was a significantly lower plasma sodium in the luteal phase, and a trend towards lower plasma osmolality.