Pharmacogenomics-Guided Individualized Treatment for Pediatric Antithyroid Drug-Associated Neutropenia: Case Report and Literature Review

Background : Antithyroid drug (ATD)-associated neutropenia is a rare yet severe adverse event in pediatric hyperthyroidism treatment, significantly increasing the risk of infection and potentially endangering life. Pharmacogenomics is a valuable auxiliary clinical tool that enables the identification of high-risk patients and the implementation of safer medication practices. Case Presentation : We present a case of a 9-year-old girl who experienced high fever and lethargy after receiving methimazole (MMI). Laboratory examination confirmed neutropenia. Conventional antibiotic treatment and granulocyte colony-stimulating factor (G-CSF) administration were unsuccessful. Subsequent pharmacogenomic testing revealed the patient's susceptibility to ATD-induced toxicity. The patient's granulocyte counts gradually normalized, and clinical symptoms improved after the drug discontinuation. After multidisciplinary consultation, radioiodine ( ¹³¹ I) therapy was ultimately chosen, resulting in favorable outcomes. Conclusion : Pharmacogenomics enhances the safety and precision of pediatric hyperthyroidism management, assists in identifying severe ATD-related adverse reactions, and provides valuable clinical insights.