Magnesium and zinc status during the menstrual cycle.

The effect of menstrual cycle phases on the indexes of magnesium and zinc status was assessed in five normally menstruating women. Plasma concentrations of magnesium and zinc and the magnesium and zinc content of red blood cells and peripheral blood mononuclear cells were measured for 3 or 5 days per week during three menstrual cycles. The cycles were divided into four phases: menses, follicular, ovulatory, and luteal. Plasma magnesium concentrations were highest during menses and then gradually declined, reaching the lowest point during the ovulatory phase. This was followed by a rise during the luteal phase. Plasma zinc concentrations were higher during menses and the follicular phase and then dropped during the ovulatory and luteal phases. Both the magnesium and zinc content of red blood cells and mononuclear cells remained constant over the course of the study and did not change significantly as a function of cycle phase. This study provides evidence that plasma magnesium and zinc concentrations fluctuate during the menstrual cycle in a phase-related fashion in normally menstruating women. Whether these changes are hormonally mediated or reflect metabolic changes will require further study.