Electrolyte disturbances in patients with chronic, stable asthma: effect of therapy.

OBJECTIVE: To determine the prevalence of electrolyte disturbances in patients with chronic, stable asthma, and to assess whether the therapeutic agents used to treat chronic asthma have an effect on abnormal electrolyte levels.
DESIGN: Prospective, hospital-based, cross-sectional study.
SETTING: University teaching hospital in Jeddah, Saudi Arabia. PATIENTS: Patients with chronic, stable asthma.
METHOD: Ninety-three consecutive patients with chronic, stable asthma were involved in the study. On the day of the visit to the asthma clinic, particulars such as age, sex, duration of asthma, and details of drug therapy were obtained from each asthmatic patient. Serum potassium, magnesium, phosphorus, calcium, and sodium levels were measured. Normal values were as follows: potassium, 3.5 to 5 mmol/L; magnesium, 0.74 to 1.2 mmol/L; phosphorus, 0.8 to 1.4 mmol/L; and calcium, 2.1 to 2.6 mmol/L.
RESULTS: Electrolyte disturbances were found in 43% of the patients; 85% of the patients had one electrolyte disturbance, 10% had two electrolyte disturbances, and 5% had three electrolyte disturbances. The highest proportions were for magnesium (26.9%) and phosphorus (15.1%) [serum levels were 0.69 +/- 0.04 mmol/L and 0.64 +/- 0.09 mmol/L, respectively], the lowest proportions were for potassium (5.4%) and sodium (4.3%) [serum levels were 3.3 +/- 0.01 mmol/L and 133 +/- 0.01 mmol/L, respectively], and no patient had a calcium disturbance. Logistic regression analysis showed no statistically significant association between the therapy used and electrolyte disturbances.
CONCLUSION: Hypomagnesemia and hypophosphatemia were found to be the two most common electrolyte disturbances in patients with chronic, stable asthma. Therapeutic agents used to treat patients with chronic asthma have no effect on abnormal electrolyte levels. The underlying cause still remains unclear.