Hypomagnesemia in chronic obstructive lung disease: effect of therapy.

In 95 patients with severe chronic airway obstruction (FEV1 33.2 +/- 12% of predicted; mean +/- SE), we investigated whether drug therapy had any influence on serum Mg levels. 11/95 patients had a serum Mg less than 1.45 mEq/l (lower normal limit). Multiple-regression analysis showed that the use of diuretics was associated with a significantly lower serum Mg level (1.59 +/- CI 0.06 mEq/l vs. an adjusted mean of 1.71 mEq/l; F = 11, 2, p less than 0.001). There was a significant negative correlation between serum Mg and the length of oral steroid therapy (1.64 +/- CI 0.02 mEq/l for less than 24 months of therapy vs. 1.52 +/- CI 0.06 mEq/l for greater than 24 months of therapy; F = 7, 3, p less than 0.005). No effect of theophylline, inhaled steroids or beta 2-agonists on serum Mg was observed. Because of potential negative effects of hypomagnesemia on respiratory function, routine serum magnesium determination is recommended in patients with chronic obstructive lung disease taking diuretic drugs or corticosteroids.