What Causes Low White Blood Cell Count?

Jun 27, 2021 Source: Cainiu Health

Dr. Xing Jian

Introduction

1. Pathological factors: In patients with viral infections, a routine blood test often reveals normal or decreased peripheral white blood cell (WBC) counts. 2. Physiological factors: WBC counts are often only mildly reduced, remaining within the lower end of the normal reference range. 3. External factors: Ionizing radiation is one of the most common causes of leukopenia; drug-induced leukopenia is another frequent cause.

Common causes of low white blood cell (WBC) count include viral infections (e.g., influenza, measles, rubella, viral hepatitis), typhoid fever, and certain medications. When foreign pathogens—such as bacteria—invade the body, white blood cells migrate to the affected site, surround, engulf, and destroy them; hence, WBCs are often referred to as the body’s “white defenders.” A reduced WBC count therefore compromises the body’s antibacterial defense, increasing susceptibility to infections. So, what causes low white blood cell counts? Below is an explanation.

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Causes of Low White Blood Cell Count

1. Pathological Factors

During routine complete blood count (CBC) testing, individuals with viral infections typically exhibit normal or decreased total WBC counts, accompanied by neutropenia (reduced neutrophil count) and a relative increase in lymphocyte count. Common viral infections—including influenza virus, measles virus, rubella virus, and viral hepatitis—may lead to leukopenia (low WBC count). Additionally, certain hematologic disorders—such as aplastic anemia, leukemia, and lymphoma—can significantly reduce circulating WBC levels.

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2. Physiological Factors

In such cases, the reduction in WBC count is usually mild and remains within the lower limit of the normal reference range, without associated clinical symptoms. No specific intervention is required; periodic follow-up CBC testing suffices. According to Traditional Chinese Medicine (TCM), leukopenia commonly arises from dual deficiencies—spleen qi deficiency progressing to liver and kidney impairment, ultimately resulting in kidney yin deficiency. Typical manifestations include fatigue, palpitations, dizziness, mucosal ulcers, and low-grade fever. Patients are advised to promptly address the leukopenia and undergo appropriate treatment.

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3. External Factors

Ionizing radiation is one of the most common external causes of leukopenia. Radiotherapy administered for treating certain diseases can suppress bone marrow function, leading to decreased WBC production. Similarly, individuals with prolonged occupational exposure to ionizing radiation may also develop leukopenia. Furthermore, drug-induced leukopenia is relatively frequent: certain medications—including antipyretic-analgesics, antithyroid agents, and sulfonamides—can adversely affect hematopoiesis and cause WBC reduction. Discontinuation of the offending drug typically results in symptom resolution.

The above outlines the primary causes of low white blood cell count. We hope this information is 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.