A decrease in serum Mg(+2) is associated with airway hyper-reactivity and impaired pulmonary function. The purpose of this study was to determine if decreased serum Mg(+2) levels in patients with chronic obstructive pulmonary disease (COPD) are associated with acute exacerbations. In a retrospective study, the charted serum Mg(+2) levels in 100 COPD patients were examined. These included 50 patients who presented with an acute exacerbation of COPD and 50 stable patients. Chart review was

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... ial within both groups. Serum Mg(2+) levels in the stable COPD patients averaged 0.91+/- 0.10 mmol/L (mean+/- SD) with a 95% CI of 0.88 - 0.94 mmol/L. Patients undergoing an exacerbation had significantly lower serum Mg(+2) levels (0.77+/- 0.10 mmol/L; CI, 0.74 - 0.79; p<0.0001). Logistic regression of the dichotomous outcomes as a function of serum Mg(+2) concentration demonstrated a highly significant association (chi(2)=41.26; p<10(-5)). These data were subjected to receiver-operator characteristic (ROC) analysis for decision levels (DL) and the area under the ROC curve was determined to be 0.85+/- 0.04 (CI, 0.78 - 0.93). The optimum DL was determined to lie between 0.80 mmol/L (OR=14.33; sensitivity 70%; specificity 86%) and 0.84 mmol/L (OR=11.16; sensitivity 84%; specificity 68%). These data suggest that at the lower range of the reference interval, serum Mg(+2) levels are associated with an increased risk of exacerbation of symptoms in COPD patients. Furthermore, they suggest a DL that is useful for predicting clinical outcomes in these patients and serving as a target value for therapy.