In a patient with status asthmaticus on a terbutaline drip, serum electrolytes are ordered because...

Beta-agonists such asterbutalineare frequently used in severe asthma to promote bronchodilation. However, these agents stimulate beta-2 receptors, which drivepotassium and phosphate into cells, leading tohypokalemia and hypophosphatemia—a well-documented side effect in patients receiving frequent or continuous beta-agonist therapy.

“Beta-adrenergic medications can cause intracellular shifting of potassium and phosphorus, especially when administered in high doses or for prolonged periods, as in status asthmaticus. This results in hypokalemia and hypophosphatemia, necessitating close electrolyte monitoring.”

(Referenced from CCRN Pediatric – Direct Care: Endocrine Disorders and Critical Pharmacologic Management)