Antithyroid Drug-Induced Agranulocytosis: State of the Art on Diagnosis and Management

Abstract

Agranulocytosis is a rare but serious complication of antithyroid drug therapy, and an up-to-date understanding of this topic is important. Both direct toxicity and immune-mediated responses have been described as possible mechanisms. Some major susceptibility loci have recently been identified, which may lead the diagnosis of agranulocytosis into a genomic era. Onset is acute and patients present with symptoms and signs of infection together with high fever. Clinical suspicion is pivotal and should prompt blood sampling. An absolute neutrophil count of <500/μl in the presence of antithyroid drugs establishes the diagnosis. The causative drug should immediately be stopped to prevent further damage. Treatment includes broad-spectrum antibiotics and granulocyte-colony stimulation factor in selected patients. Later, patients will need definitive treatment for hyperthyroidism, usually with radioactive iodine or surgery. The best way to avoid the mortality associated with antithyroid drug-induced agranulocytosis is patient education.