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

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Last updated: March 10, 2025View editorial policy

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From the Guidelines

Leukopenia is primarily caused by a combination of factors including viral infections, certain medications, autoimmune disorders, bone marrow disorders, or congenital conditions, as supported by recent studies 1. The condition is characterized by a decreased number of white blood cells (leukocytes) in the blood, specifically when the total white blood cell count falls below 4,000 cells per microliter of blood. This can be concerning because white blood cells are essential components of the immune system that help fight infections. Some key causes of leukopenia include:

  • Viral infections
  • Certain medications, such as chemotherapy drugs, antibiotics like chloramphenicol, and some psychiatric medications
  • Autoimmune disorders
  • Bone marrow disorders
  • Congenital conditions Treatment depends on the underlying cause and may include stopping the offending medication, treating infections, or using medications like granulocyte colony-stimulating factors (G-CSF) such as filgrastim (Neupogen) at doses of 5-10 mcg/kg/day subcutaneously to stimulate white blood cell production in severe cases, as recommended by recent guidelines 1. Patients with leukopenia should take precautions to avoid infections, including practicing good hand hygiene, avoiding crowds during disease outbreaks, and promptly seeking medical attention for signs of infection as their immune system is compromised. Regular blood count monitoring is essential to track the condition's progression and response to treatment, and to minimize the risk of complications such as febrile neutropenia, which can be life-threatening if not managed properly 1. It is also important to note that some genetic conditions, such as severe congenital neutropenia (SCN) and Shwachman-Diamond syndrome (SDS), can increase the risk of developing leukopenia and other hematologic malignancies, and require close monitoring and management 1.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Causes of Leukopenia

  • Leukopenia can be caused by numerous factors, including reduced production of white blood cells or increased utilization and destruction, or both 2, 3
  • Infection, drugs, malignancy, megaloblastosis, hypersplenism, and immunoneutropenia are responsible for most cases of neutropenia, a type of leukopenia 3
  • Extrinsic causes of chronic neutropenia can be varied, while intrinsic causes can include impaired proliferation and maturation of myeloid progenitor cells in the bone marrow 4
  • Certain medications, such as penicillin and cephalosporin homologues, can also cause leukopenia, especially when administered in high doses for an extended period 5

Underlying Conditions

  • Leukopenia can be a symptom of an underlying condition, such as bone marrow insufficiency, which can lead to bi- or pancytopenia 2
  • Leukopenia can also be associated with other developmental defects, particularly in children with hereditary primary neutropenia 3
  • Kidney transplantation can also lead to leukopenia, which can be managed with granulocyte colony-stimulating factor (G-CSF) and changes in immunosuppression and prophylaxis medications 6

Risk Factors

  • Patients with neutropenia are at risk of developing life-threatening bacterial infections, particularly febrile neutropenia 3, 4
  • The risk of infection is higher in patients with severe neutropenia, and these patients require prompt treatment with antibiotics 2, 4

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

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

Deutsche medizinische Wochenschrift (1946), 2017

Research

The etiology and management of leukopenia.

Canadian family physician Medecin de famille canadien, 1984

Research

Hematologic Conditions: Leukopenia.

FP essentials, 2019

Research

Leukopenia due to penicillin and cephalosporin homologues.

Archives of internal medicine, 1979

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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