Lithium Carbonate as Treatment for Paliperidone Long-Acting Injection-Induced Leukopenia and Neutropenia in a Patient With Schizophrenia: A Case Report

Schizophrenia is a chronic psychiatric disorder characterized by disturbances in thought processes, perception, emotional responsiveness, and social functioning.Second-generation antipsychotics, including clozapine, risperidone, olanzapine, and quetiapine, may rarely cause hematologic complications such as leukopenia and neutropenia.Paliperidone, the active metabolite of risperidone, has also been associated with these adverse effects.Leukopenia refers to reduced white blood cell (WBC) count, often due to neutropenia, defined as an absolute neutrophil count (ANC) of <1.50 × 10⁹/L.Lithium carbonate has been reported in case literature to increase neutrophil counts in antipsychotic-associated neutropenia, although its use remains off-label and is not included in formal treatment guidelines.We report a 23-year-old male with schizophrenia who developed progressive leukopenia and neutropenia following treatment with long-acting paliperidone.After initial stabilization on oral risperidone and monthly paliperidone injections, the patient was transitioned to a three-monthly paliperidone formulation.Routine laboratory monitoring revealed a decline in ANC and WBC levels.Other medical causes were excluded, and drug-induced neutropenia was suspected.Lithium carbonate 400 mg/day was initiated, resulting in partial improvement of hematologic parameters.However, fluctuations persisted due to intermittent non-adherence, confirmed by a subtherapeutic lithium level.Adjusting paliperidone to a lower monthly dose and reinforcing lithium adherence led to stabilization of ANC and WBC counts.The patient remained psychiatrically stable throughout follow-up.