Objective: To determine the relative frequency of hypomagnesemia among patients with chronic airflow limitation treated as outpatients at a referral center in the northern part of the state of Paraná between 2000 and 2001, as well as to determine whether hypomagnesemia correlates with hypoxia, with other electrolyte disturbances and with the severity of airflow limitation. Methods: This was a descriptive study of the relative frequency of hypomagnesemia in 72 patients with chronic airflow limitation. All of the patients were submitted to blood tests to determine serum levels of magnesium and other electrolytes, as well as to staging of the underlying disease. Results: The prevalence of hypomagnesemia was 27.8%. The mean age was 65 ± 9.9 years, and there was a predominance of males. The mean forced expiratory volume in one second was 1.31 ± 0.52 L. Most of the patients (68.1%) were found to be in the advanced stages of the disease. Hypomagnesemia was not found to correlate with other electrolyte disturbances, hypoxemia or disease stage. Conclusion: The high frequency of patients in the advanced stages is likely attributable to the fact that the outpatient facility is a referral center for the region. Further studies should be conducted in order to determine the probable causes of this high prevalence of hypomagnesemia.

Keywords: Magnesium/blood; Pulmonary ventilation; Pulmonary disease, chronic obstructive; Respiratory insufficiency