Normocytic Anemia as a Side Effect of Clozapine: A Case Report

This brief case report aims to shed light on an uncommon blood-related side effect potentially associated with clozapine use, an atypical antipsychotic primarily prescribed for treatment-resistant schizophrenia. A 70-year-old white male with a significant past medical history of schizophrenia controlled with clozapine was evaluated over approximately two months. Regular blood work was conducted to monitor his absolute neutrophil count, which is known to drop while on clozapine. During his stay, it was noticed that his hemoglobin levels were declining without a clear reason. Through the method of exclusion, the most common causes of anemia were ruled out, and it was determined that the patient's anemia was secondary to clozapine, a side effect that is not commonly reported. The precise mechanism by which clozapine affects hemoglobin levels remains unclear. However, some studies suggest potential direct bone marrow toxicity. This is supported by the rapid improvement in hemoglobin observed after clozapine discontinuation in this case. This case highlights a potential association between clozapine use and normocytic anemia. It emphasizes the significance of regular blood work monitoring not only for the absolute neutrophil count but also for hemoglobin. This rare case underscores the importance of considering red blood cell parameters in patients on clozapine, offering insights that go beyond the commonly reported agranulocytosis side effect and potentially expanding awareness of adverse hematological effects associated with this antipsychotic medication. Further research is crucial to unravel the underlying mechanisms and establish definitive causality.