Sex steroid hormones modulate serum ionized magnesium and calcium levels throughout the menstrual cycle in women.

OBJECTIVE: To determine the serum concentrations of the sex steroid hormones with respect to the concentrations of the biologically active fractions of magnesium and calcium during the different phases of the menstrual cycle.
DESIGN: Controlled clinical study.
SETTING: An academic research environment. PATIENT(S): Six parous and four nulliparous healthy cycling female volunteers. MAIN OUTCOME MEASURE(S): Concentrations of the sex steroid hormones estrogen, progesterone, and testosterone as well as the ionized Ca and Mg levels were measured in the serum of normal cycling women during five different stages: the menstrual, early follicular, late follicular, ovulatory (ovulatory/early luteal), and luteal phases. RESULT(S): In each woman, there was a comparatively high ionized Mg level coincident with the early follicular phase, a statistically significant decrease in ionized Mg around the time of ovulation, a significant decrease in ionized and total Mg when the serum progesterone concentration peaked, and a significant increase in the serum Ca2+/Mg2+ ratio at both the ovulatory and luteal phases. In addition, a decrease in ionized Mg was found with increased testosterone levels. CONCLUSION(S): Healthy women of reproductive age demonstrate recurring cycling of ionized Mg and cyclic alterations in the ionized Ca to Mg ratio in their serum. The changes in serum concentrations of these important physiologically active cations, in the range at which they occur, can affect such entities as the vasculature, synaptic transmission, and excitation-secretion coupling and thus can produce the well-known premenstrual syndromes during the luteal phase in women who are somewhat deficient in Mg or in those who have an unusually increased Ca2+/Mg2+ ratio.