Location
Philadelphia, PA
Start Date
30-4-2025 1:00 PM
End Date
30-4-2025 4:00 PM
Description
INTRODUCTION: Clozapine is widely known for its life-threatening, albeit rare, adverse effect, agranulocytosis. However, a paradoxical and underreported finding, neutrophilic leukocytosis, defined as an increase in ANC above 7700 neutrophils/µL and white blood cell (WBC) count above 11,000 cells/µL may occur. We report the case of one individual with asymptomatic transient neutrophilic leukocytosis following Clozapine initiation.
OBJECTIVE: The objective of this case study is to provide supporting literature about the benign nature of clozapine-induced neutrophilic leukocytosis. This information may assist physicians’ decision-making, as this finding does not necessarily warrant cessation of the medication.
METHODS: This case report was compiled using patient records, labs, and real-time interviews. A thorough analysis of several peer-reviewed literature sources was used. A broad search was conducted using credible databases, including PubMed, Google Scholar, ScienceDirect, and UpToDate.
RESULTS: Neutrophilia typically occurs in the setting of infection, inflammation, and malignancies, but medications can also precipitate neutrophilia through various mechanisms. Neutrophilia may occur within minutes to hours following drug administration via demargination and increased bone marrow release. Neutrophilia could also occur within days to weeks via allergic reactions, increased proliferation, and or differentiation. We report the case of a patient with treatment-resistant schizoaffective disorder bipolar type who experienced asymptomatic transient neutrophilic leukocytosis following the admission of Clozapine. The reaction appeared transient as it was only noted on one set of labs.
The clearest evidence that the transient neutrophilic leukocytosis was induced by Clozapine was the downward trend to baseline labs seen before discontinuation of Clozapine with the eventual return to baseline seen after complete cessation. This patient's medical history included an acquired splenectomy, which may have precipitated the abnormal lab findings.
CONCLUSION: Neutrophilic leukocytosis is not mentioned as an adverse side effect in the Clozapine manufacturer's full prescribing information. Physicians unaware of this side effect, and more particularly its benign nature, may stop the medication altogether. Cessation of clozapine is not recommended in this setting, especially as it is often a last-resort treatment option.
Embargo Period
5-29-2025
Included in
Transient Neutrophilic Leukocytosis following Clozapine initiation: A Case Study
Philadelphia, PA
INTRODUCTION: Clozapine is widely known for its life-threatening, albeit rare, adverse effect, agranulocytosis. However, a paradoxical and underreported finding, neutrophilic leukocytosis, defined as an increase in ANC above 7700 neutrophils/µL and white blood cell (WBC) count above 11,000 cells/µL may occur. We report the case of one individual with asymptomatic transient neutrophilic leukocytosis following Clozapine initiation.
OBJECTIVE: The objective of this case study is to provide supporting literature about the benign nature of clozapine-induced neutrophilic leukocytosis. This information may assist physicians’ decision-making, as this finding does not necessarily warrant cessation of the medication.
METHODS: This case report was compiled using patient records, labs, and real-time interviews. A thorough analysis of several peer-reviewed literature sources was used. A broad search was conducted using credible databases, including PubMed, Google Scholar, ScienceDirect, and UpToDate.
RESULTS: Neutrophilia typically occurs in the setting of infection, inflammation, and malignancies, but medications can also precipitate neutrophilia through various mechanisms. Neutrophilia may occur within minutes to hours following drug administration via demargination and increased bone marrow release. Neutrophilia could also occur within days to weeks via allergic reactions, increased proliferation, and or differentiation. We report the case of a patient with treatment-resistant schizoaffective disorder bipolar type who experienced asymptomatic transient neutrophilic leukocytosis following the admission of Clozapine. The reaction appeared transient as it was only noted on one set of labs.
The clearest evidence that the transient neutrophilic leukocytosis was induced by Clozapine was the downward trend to baseline labs seen before discontinuation of Clozapine with the eventual return to baseline seen after complete cessation. This patient's medical history included an acquired splenectomy, which may have precipitated the abnormal lab findings.
CONCLUSION: Neutrophilic leukocytosis is not mentioned as an adverse side effect in the Clozapine manufacturer's full prescribing information. Physicians unaware of this side effect, and more particularly its benign nature, may stop the medication altogether. Cessation of clozapine is not recommended in this setting, especially as it is often a last-resort treatment option.
Comments
Awarded "Division of Research Award for Best Case Study" at PCOM Research Day 2025.