Which adverse effect is most concerning and commonly monitored with methimazole and propylthiouracil in thyroid storm management?

• A. Agranulocytosis
• B. Hepatotoxicity
• C. Hypertension
• D. Hypokalemia

Answer: (A)

Agranulocytosis is the most concerning adverse effect with methimazole and propylthiouracil in thyroid storm management because these drugs can cause a dangerous drop in neutrophils, leaving a patient highly susceptible to severe, potentially life-threatening infections. This is why clinicians routinely obtain a baseline white blood cell count and neutrophil count before starting therapy and monitor CBCs during treatment, along with watching for warning signs like fever, sore throat, or mouth ulcers. If agranulocytosis develops, the antithyroid drug is stopped and the patient receives appropriate infection management.

Hepatotoxicity is a valid concern, particularly with propylthiouracil, but it is not the adverse effect that's monitored as routinely or as urgently as agranulocytosis in the acute thyroid storm setting. Hypertension and hypokalemia are not characteristic adverse effects of these medications in this context.