Reduced intracellular Mg concentrations in patients with acute asthma

STUDY OBJECTIVES: To determine the intracellular and extracellular Mg concentrations in patients with acute asthma and their correlation with parameters expressing the disease severity. PATIENTS: Thirty patients with acute asthma (FEV(1), 56% predicted [SD, 14.5]), 20 patients with stable asthma (FEV(1), 97% predicted [SD, 10]), and 20 healthy subjects (FEV(1), 97% predicted [SD, 8]). METHODS: Mg concentrations in erythrocytes and plasma were measured four times: at hospital admission, after 2 days, after 5 days, and at hospital discharge. Percentage of predicted FEV(1) and peak expiratory flow rate variability were recorded simultaneously. Similar measurements were carried in all study groups. RESULTS: Mg concentrations of healthy subjects and patients with stable asthma remained unchanged in both plasma and erythrocytes. Initial Mg content in erythrocytes was significantly lower in patients with acute asthma (1.77 fmmol per cell; 95% confidence interval [CI], 1.71 to 1.83) compared to normal subjects (1.94 fmmol per cell; 95% CI, 1.82 to 2.00) and patients with stable asthma (1.92 fmmol per cell; 95% CI, 1.87 to 1.96) [p < 0.0001], and it increased significantly after the resolution of the exacerbation (from 1.77 fmmol per cell [95% CI, 1.71 to 1.83] at hospital admission to 1.90 fmmol per cell [95% CI, 1.83 to 1.98] at hospital discharge; p < 0.0001). No correlation was observed between parameters of disease severity and the initial values of Mg concentrations in erythrocytes and plasma. CONCLUSIONS: Acute asthma is associated with lower erythrocyte Mg content while plasma levels remain unchanged. This decrease in intracellular Mg content occurs regardless of the severity of the exacerbation and returns to normal values after control has been achieved.