A study of the renal sodium excretion during the normal menstrual cycle using method of passive leg rising

12 healthy women (age 18-38 years) were examined using the 2-hour's method of passive leg rising (PLR) in follicular (FP) and luteal (LP) phases of normal ovulatory cycle. Renal and hormonal response to PLR was investigated. There was a significant increase of diuresis (from 53 +/- 9 ml/h to 298 +/- 27 ml/h in FP, from 69 +/- 12 to 324 +/- 28 ml/h in LP) and natriuresis (from 4.5 +/- 0.9 to 9.8 +/- 1 mmol/h in FP, from 5.7 +/- 0.3 to 12.1 +/- 1.1 mmol/h in LP), simultaneously with a decrease of plasma renin activity (PRA) and plasma aldosterone (PA) in both FP and LP. Baseline PRA was mildly and PA was significantly higher in LP compared to FP. Urinary osmolarity, heart rate and systolic blood pressure dropped significantly. Renal and hormonal response to PLR were identical in the two phases of the menstrual cycle. Authors conclude that 1/PLR causes significant diuresis and natriuresis due to central volume expansion and may be used as a simple stimulating test of renal sodium excretion, 2/renal sodium retention does not occur in the LP of normal ovulatory cycle.