Changes in plasma sodium concentration in women at the menopause

A significant increase in the mean plasma sodium concentration and in the fasting urinary Na/Cr ratio was observed in healthy women at the menopause. Both of these changes were reversed by administering oestrogens. None of the above effects appeared to be due to alterations in sodium intake or in renal glomerular function. The most likely cause of the increase in plasma sodium concentration at the menopause appeared to be a decrease in plasma volume since there were also significant increases in the mean plasma albumin and total protein concentrations.