Carbimazole-Induced Agranulocytosis in a Previously Stable Patient: A Case Report and Literature Review

Carbimazole-induced agranulocytosis is a rare condition. A 48-year-old female patient with a history of hyperthyroidism for several years presented with generalized fatigue and chest pain associated with palpitations; the patient was stable on carbimazole therapy. She was previously on carbimazole 15 mg once daily (OD) and, three months later, was reduced to 10 mg OD as symptoms were controlled. She was taking propranolol, and it was stopped as she was not having any palpitations. This time, however, she presented mainly with palpitations at night associated with chest pain and generalized fatigue ongoing for the last one week. Her laboratory results showed agranulocytosis with reduced white cell count and neutrophil count in the absence of any evidence of infection. Her carbimazole was stopped, and the patient was referred to ear, nose, and throat surgeons for consideration of thyroidectomy. The patient underwent subtotal thyroidectomy, and her symptoms resolved following surgery.