A pilot study of erythrocyte lithium-sodium countertransport in women during the menstrual cycle.

The study investigated lithium-sodium countertransport in erythrocytes of normal female volunteers during different phases of the menstrual cycle or during administration of oral contraceptives.Ten normally menstruating, and eight oral contraceptive using, normal female subjects were studied over at least one cycle. Erythrocyte lithium-sodium countertransport was determined using. standard, previously validated methods at different phases of the menstrual cycle. Hematological, electrolyte, blood pressure and other transport measures were also made and these were related to the self-reported incidence of premenstrual symptomatology.A correlation, (p < 0.02), was found between lithium-sodium countertransport rate and the premenstrual symptom severity score but only in the premenstrual phase. There was no correlation between any of the electrolyte, blood pressure or hematological data and lithium-sodium countertransport rate nor between it and other ion transport measures. Pre-menstrual symptomatology was co...