What is the cause of Leukopenia (low White Blood Cell count)?

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Last updated: May 6, 2025View editorial policy

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From the Guidelines

Leukopenia should be managed by identifying and treating the underlying cause, and in severe cases, granulocyte colony-stimulating factors like filgrastim (Neupogen) at 5-10 mcg/kg/day subcutaneously may be prescribed to stimulate white blood cell production, as recommended by recent guidelines 1. Leukopenia is a condition characterized by an abnormally low white blood cell count (typically below 4,000 cells per microliter of blood). This condition increases susceptibility to infections as white blood cells are crucial components of the immune system. Leukopenia can result from various causes including viral infections, certain medications (chemotherapy drugs, antibiotics like chloramphenicol), autoimmune disorders, bone marrow disorders, or congenital conditions.

Causes and Management

  • Medication-induced leukopenia: discontinuing the offending drug may be necessary
  • Severe cases: granulocyte colony-stimulating factors like filgrastim (Neupogen) at 5-10 mcg/kg/day subcutaneously may be prescribed to stimulate white blood cell production
  • Patients with leukopenia should take precautions to prevent infections, including practicing good hygiene, avoiding crowds during illness outbreaks, and promptly reporting fever or other infection signs
  • Regular blood count monitoring is essential for tracking recovery The condition's severity varies based on which white blood cell types are affected and how low the counts fall, with neutropenia (low neutrophil count) being particularly concerning due to increased infection risk, as seen in studies 1.

Prevention of Infections

  • Practicing good hygiene
  • Avoiding crowds during illness outbreaks
  • Promptly reporting fever or other infection signs It is essential to note that the use of hematopoietic growth factors, such as G-CSF, should be reserved for patients with febrile neutropenia or those at high risk of infection, as recommended by guidelines 1.

From the Research

Definition and Causes of Leukopenia

  • Leukopenia is an abnormal reduction of circulating white blood cells, especially the granulocytes 2.
  • The term leukopenia is often used interchangeably with neutropenia 2.
  • Leukopenia may result from reduced production of white blood cells or increased utilization and destruction, or both 2.
  • Infection, drugs, malignancy, megaloblastosis, hypersplenism, and immunoneutropenia are responsible for most cases of neutropenia 2.

Diagnosis and Management of Leukopenia

  • Checking previous blood counts of the patient can help identify the dynamic development of leukopenia 3.
  • A manual counted peripheral blood smear is an essential step towards the right diagnosis in leukopenia, providing information on potential causes such as dysplasia 3.
  • Leukopenia can be life-threatening, especially if the patient presents with agranulocytosis and fever, requiring immediate treatment with broad-spectrum antibiotics 3.
  • Management of leukopenia requires identification of the cause and effective antimicrobial therapy, especially when serious systemic infection is present 2.

Treatment of Neutropenia with Filgrastim and Pegfilgrastim

  • Filgrastim and pegfilgrastim are used to assist recovery in patients with low white blood cell counts 4.
  • Pegfilgrastim is a PEGylated formulation of filgrastim with a long half-life, which can cause a temporary increase in white blood cell count, including a leukocyte overshoot 5.
  • The incidence and timing of leukocyte overshoot after pegfilgrastim administration have been studied, with results showing a higher frequency of occurrence when blood is collected 1-2 days after administration 5.
  • Pegfilgrastim appears equivalent to daily dosing of filgrastim to treat neutropenia after autologous peripheral blood stem cell transplantation in patients with non-Hodgkin lymphoma 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

The etiology and management of leukopenia.

Canadian family physician Medecin de famille canadien, 1984

Research

[Leukopenia - A Diagnostic Guideline for the Clinical Routine].

Deutsche medizinische Wochenschrift (1946), 2017

Research

Filgrastim and pegfilgrastim use in patients with neutropenia.

Clinical journal of oncology nursing, 2009

Research

The incidence and timing of leukocyte overshoot after pegfilgrastim administration.

Journal of oncology pharmacy practice : official publication of the International Society of Oncology Pharmacy Practitioners, 2019

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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