Hypomagnesemia and bronchial hyperreactivity

In a 37-year-old woman, a heavy smoker and an alcoholic, bronchial hyperreactivity to histamine (PC20 FEV1 0.8 mg/ml) was related to hypomagnesemia (0.55 mmol/l). After acute magnesium repletion (24 h i.v. infusion MgSO4 6 g, serum magnesium 1.05 mmol/l), histamine PC20 FEV1 increased up to 9.8 mg/ml. The role of magnesium in modulating smooth muscle contractility is discussed and the importance of checking serum magnesium in patients with airway obstruction is suggested.