What causes leukopenia (low White Blood Cell count)?

From the Guidelines

A low white blood cell (WBC) count, or leukopenia, can be caused by several factors, including viral infections, certain medications, bone marrow disorders, autoimmune diseases, nutritional deficiencies, congenital disorders, radiation exposure, and severe infections. According to the most recent study 1, which provides an update on recommendations for surveillance for children with predisposition to hematopoietic malignancy, certain genetic mutations can increase the risk of developing leukemia and other blood disorders, leading to leukopenia.

Some key factors that can cause a low WBC count include:

• Viral infections, such as influenza, HIV, and COVID-19, which can temporarily suppress bone marrow function 1
• Certain medications, such as chemotherapy drugs, some antibiotics like trimethoprim-sulfamethoxazole, antipsychotics like clozapine, and immunosuppressants like methotrexate and azathioprine 1
• Bone marrow disorders, such as leukemia, myelodysplastic syndrome, and aplastic anemia, which directly affect WBC production 1
• Autoimmune diseases, including lupus and rheumatoid arthritis, which can destroy white blood cells or impair their production 1
• Nutritional deficiencies, especially vitamin B12, folate, and copper, which are important reversible causes 1
• Congenital disorders, such as Kostmann syndrome and cyclic neutropenia, which represent genetic causes 1
• Radiation exposure and severe infections causing sepsis, which can also reduce WBC counts 1

It's essential to seek medical evaluation to determine the underlying cause of a low WBC count, as treatment depends on identifying the specific reason for the deficiency. The most critical step is to consult a healthcare professional for a thorough evaluation and guidance on the appropriate course of treatment.

From the FDA Drug Label

Hematologic:Agranulocytosis, aplastic anemia, thrombocytopenia, leukopenia, neutropenia, hemolytic anemia, megaloblastic anemia, hypoprothrombinemia, methemoglobinemia, eosinophilia, thrombotic thrombocytopenic purpura, idiopathic thrombocytopenic purpura

• Low WBC can be caused by:
  • Agranulocytosis
  • Aplastic anemia
  • Leukopenia
  • Neutropenia 2

From the Research

Causes of Low White Blood Cell Count

• Infection, drugs, malignancy, megaloblastosis, hypersplenism, and immunoneutropenia can cause a low white blood cell count, also known as leukopenia 3
• Neutropenia, a type of leukopenia, can be caused by reduced production of white blood cells or increased utilization and destruction, and can be classified as transient or chronic 4
• Extrinsic causes of chronic neutropenia can include impaired proliferation and maturation of myeloid progenitor cells in the bone marrow, while intrinsic causes can include drug-induced immune neutropenia/agranulocytosis 4, 5
• Certain drugs, such as dipyrone, diclofenac, ticlopidine, and antithyroid drugs, can cause neutropenia or agranulocytosis by inducing the formation of drug-dependent antibodies against neutrophil membrane glycoproteins 5
• Chemotherapy can also cause leukopenia, and the severity of leukopenia has been associated with the survival of patients with small-cell lung cancer 6

Other Factors

• HIV therapy, including chemotherapy, can also affect white blood cell count, and chronic therapy can result in toxicity 7
• The risk of infection is a major concern for individuals with a low white blood cell count, and treatment with antibiotics may be necessary in cases of febrile neutropenia 3, 4