Valproic acid-induced neutropenia

OBJECTIVE: To report a case of severe neutropenia caused by valproic acid (VPA). CASE SUMMARY: A 56-year-old white woman with an infectious brain abscess causing tonic-clonic seizure activity was treated with VPA. She developed severe neutropenia after 2 days of VPA therapy. The absolute neutrophil count reached a nadir of 47 cells/mm(3) during VPA use and returned to normal upon its discontinuation. DISCUSSION: VPA is considered to be a well-tolerated antiepileptic drug. While neutropenia has been reported, it has been mild and transient. This patient developed severe neutropenia during effective treatment with VPA, making her significantly susceptible to infection. The Naranjo probability scale indicates VPA as the probable cause of neutropenia in this case. CONCLUSIONS: This report of severe neutropenia caused by VPA emphasizes the importance of monitoring complete blood cell counts during therapy with this agent.