Effect of menstrual cycle phase and oral contraceptive use on serum lithium levels after a loading dose of lithium in normal women

Serum lithium levels were analyzed in six healthy, normal women during the midfollicular, midluteal, and premenstrual phases of their menstrual cycles after they had received 300 mg of lithium carbonate orally. An identical protocol was followed for seven women with artificial cycles induced by oral contraceptive steroids. Analysis of variance for repeated measures over time showed no significant differences between groups or between cycle phases. Therefore, hormonal effects of ovarian or contraceptive steroids per se do not appear to alter serum lithium concentrations. Other factors may account for changing lithium requirements during the menstrual cycle in some patients with affective illness.