Serum ionized magnesium and calcium levels in adult patients with seizures.

OBJECTIVE: Prior studies have been equivocal about whether or not serum levels of the divalent ions calcium and magnesium are altered during different types of seizures. Magnesium is a potential modulator of seizure activity because of its ability to antagonize the excitatory calcium influx through the N-methyl-D-aspartate (NMDA) receptor. We hypothesize that serum ionized levels of calcium (Ca(2+)) and magnesium (Mg(2+)) would be altered significantly during certain types of seizures.

MATERIAL AND METHODS: A convenience sample of seizure patients presenting to an emergency department (ED) were enrolled in this prospective study. Novel ion-selective electrodes were used to measure Ca(2+) and Mg(2+). Data were reported as mean values+/-standard deviations. Group comparisons were analyzed by ANOVA with post-hoc testing using the Bonferroni, or the Fisher exact test, where appropriate, alpha = 0.05 (two-tailed).

RESULTS: Forty-nine patients with seizure and 32 healthy racially matched controls were included in the study. Seizure patients had a significantly (p<0.001) lower mean Mg(2+), but not total serum Mg and a significantly (p<0.001) higher Ca(2+)/Mg(2+) ratio than that in controls.

CONCLUSIONS: We were able to show significantly lower Mg(2+) and higher ionized Ca(2+)/Mg(2+) ratios in seizure patients compared with a racially matched control group.