METABOLIC CORRELATES OF THEOPHYLLINE THERAPY - A CONCENTRATION-RELATED PHENOMENON

OBJECTIVE: To determine the relationship of serum theophylline concent ration with electrolyte and glucose abnormalities across a broad range of theophylline concentrations. DESIGN: Retrospective review of a com puterized laboratory database between June 1, 1984 arid June 1, 1986. SETTING: A midwestern university medical center. PATIENTS: Eight hundr ed sixty-nine patients with serum theophylline concentrations of >5.5 mumol/L and a random unmatched sample (control group) of 350 in- and o utpatient adults and children with no history of reactive airways dise ase or theophylline exposure. RESULTS: Patients with measurable theoph ylline had a higher risk of hypokalemia, hyponatremia, hyperglycemia, hypophosphatemia, and hypomagnesemia compared with the unexposed contr ol group. Unadjusted odds ratios (OR) were: (1) hypokalemia OR=4.2 (95 percent CI 2.2 to 7.9); (2) hyponatremia OR=5.4 (95 percent CI 2.0 to 12.9); (3) hypomagnesemia OR=1.6 (95 percent CI 1.0 to 2.5); (4) hype rglycemia OR=2.3 (95 percent CI 1.7 to 3.0); and (5) hypophosphatemia OR=2.7 (95 percent CI 1.2 to 5.3). A linear concentration-response rel ationship was documented between serum theophylline concentration and all metabolic disturbances. CONCLUSIONS: Measurable theophylline was a ssociated with increased risk for glucose and electrolyte abnormalitie s in a concentration-related fashion across a broad range of theophyll ine concentrations from 5.5 to greater-than-or-equal-to 110 mumol/L.