SEVERE HYPERCALCEMIA SECONDARY TO THEOPHYLLINE TOXICITY

A 41-year-old asthmatic woman presented to our emergency department ex hibiting symptoms of lethargy, respiratory distress, and tachycardia. Baseline laboratory investigation revealed a significantly elevated th eophylline level as well as marked hypercalcemia (calcium = 16.0 mg/dL ). Serum calcium normalized after theophylline was discontinued. The u nusual level of hypercalcemia secondary to theophylline toxicity may h ave been related to the action of beta agonists (used in conjunction w ith theophylline to treat bronchospasm), dehydration, or concomitant m ild hyperthyroidism. Suppressed parathyroid hormone (PTH) and 1-25 dih ydroxy vitamin D levels measured in our patient suggest a mode of acti on for theophylline-induced hypercalcemia that is completely independe nt of PTH action.