Plasma and Membrane Ca²⁺ and Mg²⁺ Concentrations in Normal Pregnancy and in Preeclampsia

Objective: Changes in intracellular Ca²⁺ and Mg²⁺ concentrations seem to be involved in the pathogenesis of preeclampsia, whereas the role of cell membranes has not been studied in detail yet. To investigate the changes in Ca²⁺ and Mg²⁺ metabolism in normal pregnancy and preeclampsia, plasma and membrane Ca²⁺ and Mg²⁺ concentrations were determined in a clinical study as compared to healthy subjects. Study Design: 25 healthy female subjects, 22 untreated healthy pregnant and 20 preeclamptic women were investigated. In each patient, plasma and membrane Ca²⁺ and Mg²⁺ content were measured. Ca²⁺ and Mg²⁺ concentrations were measured by atomic absorption spectroscopy. Erythrocyte membranes were chosen for membranous Ca²⁺ and Mg²⁺ determination. Results: Plasma Mg²⁺ concentrations were significantly lowered in the healthy pregnant group and the preeclamptic group as compared to contols (p < 0.0001). In erythrocyte membranes, Mg²⁺ content was found significantly decreased in the preeclamptic women as compared to healthy subjects (p < 0.001). In plasma Ca²⁺ concentrations there was a significant decrease in the preeclamptic group as compared to controls or healthy pregnant women (p < 0.05). Membranous Ca²⁺ content was significantly increased in the preeclamptic group versus controls or healthy pregnant women (p < 0.001). Conclusion: Lowered plasma and membrane Mg²⁺ concentrations in preeclampsia may contribute to the development of hypertension in pregnancy. Additionally, a disturbed Ca²⁺ homeostasis is observed in preeclampsia.