Psychophysiological aspects of the menstrual cycle.

After a survey of literature on electrolyte changes associated with the varying excretion of hormones during the menstrual cycle, a study of 30 women aged 18-33 is reported. Measurements of sodium and potassium ions in the saliva were made at 4 points in the menstrual cycle and, since previous work had shown bilateral asymmetry in sodium reabsorption in the eccrine sweat glands, samples were collected from both the right and left sides of the mouth. The smallest sodium/potassium (Na+/K+) ratios were found at ovulation and the premenstruum. This fits 2 sets of facts: 1) during stress Na+/K+ ratios decrease and 2) this decrease comes exactly when most women report feelings of irritability, anxiety, and such. Differences in Na+/K+ ratios over points in the cycle were significant at p less than .001. Differences between right and left side were significant during the premenstruum (p less than .05). K+ was highest at ovulation (p less than .001) and the left side produced higher values (p less than .05). Na+ was lowest at ovulation, highest at menstruation (p less than .001) with concentration on right side higher at menstruation (p less than .05). This seems to indicate that the right side not only reabsorbs Na+ more efficiently but it can also excrete more efficiently and maintains homeostasis more effectively. Estrogen seems to play a major role in initiating these variations in body electrolytes, which are similar to stress reactions. It is also suggested that salivary electrolytes, recorded for parotid saliva, reflect readings similar to that of plasma with Na+ and K+ tending to move in opposite directions.