Methimazole-induced Agranulocytosis Complicated by Thyrotoxic Crisis: A Case Report
Koppula Sirisha *
Department of Pharmacy Practice, KVSR Siddhartha College of Pharmaceutical Sciences, India.
Rajagiri Triveni
Department of Pharmacy Practice, KVSR Siddhartha College of Pharmaceutical Sciences, India.
Nalam Vineela Nirmala
KVSR Siddhartha College of Pharmaceutical Sciences, India.
Lingineni Mani Deepa Chandrika
KVSR Siddhartha College of Pharmaceutical Sciences, India.
Muthineni Pradeep Kumar
KVSR Siddhartha College of Pharmaceutical Sciences, India.
Motupalli Poojitha
KVSR Siddhartha College of Pharmaceutical Sciences, India.
Sayyed Arshad
KVSR Siddhartha College of Pharmaceutical Sciences, India.
*Author to whom correspondence should be addressed.
Abstract
Methimazole is one of the most commonly used drugs in the management of hyperthyroidism but rarely leads to potentially life-threatening agranulocytosis, which can significantly complicate clinical management. We report the case of a 49-year-old male with a known history of hyperthyroidism for ten years who presented with high-grade fever, profuse sweating, cough with expectoration, reeling sensation, shortness of breath, and generalized weakness following methimazole therapy. Laboratory investigations revealed profound agranulocytosis with an absolute neutrophil count below 500/µL, along with marked thyrotoxicosis, raising suspicion of an evolving thyrotoxic crisis. Methimazole was immediately discontinued, and treatment with broad-spectrum intravenous antibiotics, granulocyte-colony stimulating factor, beta-blockers, corticosteroids, and supportive care was initiated. The patient showed significant clinical and hematological improvement with recovery of neutrophil counts and stabilization of thyroid function and was discharged in a stable condition. This case emphasizes the need for early recognition of methimazole-induced agranulocytosis, which may progress to severe and life-threatening complications. Timely withdrawal of the offending drug along with early multidisciplinary intervention is crucial in reducing morbidity and preventing fatal outcomes.
Keywords: Methimazole, agranulocytosis, thyrotoxic crisis, hyperthyroidism, antithyroid drugs, adverse drug reaction