What Causes Low White Blood Cell Count?

Dec 04, 2021 Source: Cainiu Health

Dr. Qi Zhirong

Introduction

1. Hematologic disorders: Leukopenia is commonly associated with hematologic diseases, which can occur at any age and affect both genders equally. 2. Infections (e.g., common cold): Certain infections and conditions—such as aplastic anemia, myelofibrosis, and bone marrow hematopoietic arrest—can also lead to leukopenia. 3. Autoimmune disorders: Autoimmune conditions, including rheumatoid arthritis, may likewise present with low white blood cell counts.

Leukopenia—also known as low white blood cell (WBC) count—is a condition that may arise either from unknown causes or secondary to other underlying diseases. It is broadly classified into two categories: primary and secondary. Primary leukopenia has no identifiable cause, whereas secondary leukopenia may result from acute infections; physical or chemical factors (e.g., radiation or toxins); hematologic disorders; splenomegaly-associated conditions; connective tissue diseases; allergic disorders; inherited disorders; or acquired or idiopathic neutropenia. Below, we address the question: What are the causes of leukopenia?

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What Causes Leukopenia?

1. Hematologic Disorders

Leukopenia is commonly associated with hematologic diseases, affecting individuals of any age and both sexes equally. Clinically, it can be categorized into idiopathic (cause unknown) and persistent forms; the former is more common, while the latter is often attributable to chemical or physical agents—including certain medications. Examples include post-chemotherapy cytopenia and various hematologic malignancies. According to Traditional Chinese Medicine (TCM), leukopenia involves dysfunction of the heart, liver, spleen, and kidneys—with particularly close associations to the spleen and kidneys. As the kidneys are regarded in TCM as “the root of congenital constitution,” kidney health must be carefully preserved.

2. Common Cold (Viral Upper Respiratory Infection)

Hematologic disorders constitute a major cause of leukopenia. Other conditions—including aplastic anemia, myelofibrosis, and bone marrow failure—may also lead to reduced WBC counts. These disorders typically feature not only leukopenia but also concurrent reductions in other blood cell lineages, such as anemia (low red blood cells) and thrombocytopenia (low platelets). Mild leukopenia generally does not warrant excessive concern—provided the absolute neutrophil count remains ≥1.5 × 10⁹/L—since patients usually remain asymptomatic and are not at significantly increased risk of infection. However, extremely low WBC counts require prompt clinical evaluation.

3. Immune-Mediated Disorders

Autoimmune or immune-mediated diseases—such as rheumatoid arthritis—can also manifest with leukopenia. When WBC counts fall markedly, pharmacologic intervention may be required. Among hematologic disorders causing leukopenia are megaloblastic anemia, severe iron-deficiency anemia, aplastic anemia, and non-leukemic leukemia—all of which may present with decreased WBC counts.

4. Viral Hepatitis

Viral hepatitis may induce leukopenia. Diagnosis can be supported by evaluating the WBC count during routine liver function testing. Patients suspected of having viral hepatitis should seek evaluation and management at a specialized hepatology center.

The above outlines the principal causes of leukopenia. We hope this information proves helpful to you.

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Does AIDS cause a decrease or increase in white blood cells?

In general, AIDS refers to acquired immunodeficiency syndrome. Whether acquired immunodeficiency syndrome causes a decrease or increase in white blood cells depends on the specific situation. In the early stages of acquired immunodeficiency syndrome, white blood cell counts typically increase; however, during the middle to late stages of acquired immunodeficiency syndrome, white blood cell counts may decrease.