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Leukopenia

Leukopenia, also known as neutropenia or low white blood cell count, is a medical condition characterized by an abnormally low level of white blood cells (leukocytes) in the blood, measured at fewer than approximately 4.0 × 10^9 cells per liter. This condition can arise from various factors, including the use of certain medications, radiation therapy, severe infections, or underlying bone marrow diseases such as leukemia and aplastic anemia. Individuals over 70 and those with pre-existing health conditions like diabetes are particularly vulnerable to leukopenia, especially during chemotherapy treatments.

Leukocytes play a crucial role in the immune system by fighting off infections; thus, a reduction in their number significantly increases the risk of infections, which could lead to severe complications like septicemia. Symptoms of leukopenia often include recurrent infections, fever, chills, and mouth ulcers, and diagnosis is typically confirmed through a blood test. Treatment usually involves administering hematopoietic growth factors to stimulate white blood cell production, as traditional white blood cell transfusions are not feasible due to their short lifespan. If left untreated, leukopenia can result in life-threatening conditions, making timely medical intervention essential.

Full Article

  • ALSO KNOWN AS: Neutropenia, low white blood cell count, leucopenia
  • RELATED CONDITIONS: Neutropenia, a type of leukopenia

DEFINITION: Leukopenia is an abnormally low number of white blood cells, or leukocytes. The laboratory standard measurement of leukocytes ranges from approximately 4.0 to 11.0 × 109 cells per liter of blood.

Risk factors. Leukopenia may be related to the use of certain drugs (such as barbiturates and chemotherapeutics), radiation therapy, bone marrow or stem cell transplant, severe infections, or bone marrow diseases such as leukemia, myelodysplastic syndromes, acquired immunodeficiency syndrome (AIDS), aplastic anemia, or lupus. Patients older than seventy and those with comorbid diseases, such as diabetes, are at great risk for leukopenia during chemotherapy.

Etiology and the disease process. Chemotherapy and radiation therapy for cancer target the rapidly dividing cancer cells and other rapidly dividing cells, that is, hematopoietic stem cells. It takes about ten days for a new leukocyte to differentiate and mature from a hematopoietic stem cell, meaning that a patient receiving chemotherapy or radiation therapy can have fewer leukocytes for days. The role of leukocytes is to safeguard against infection by destroying bacteria. Leukopenia and its associated impaired immunity make a patient more susceptible to infections and may lead to septicemia. Untreated leukopenia may require hospitalization and use of intravenous anti-infective drugs.

Incidence. Most patients receiving chemotherapy, radiation therapy, or a bone marrow transplant experience leukopenia, which often delays chemotherapy.

Symptoms. Symptoms include recurrent infections, high-grade fever and chills, sore throat, cough, mouth ulcers, light-headedness, and diarrhea.

Screening and diagnosis. Leukopenia is defined as a leukocyte count less than approximately 4.0 × 109 per liter. Mild leukopenia is defined as a leukocyte count of 1.0 to 2.0 × 109 per liter, and severe leukopenia is defined as a leukocyte count of less than 0.5 × 109 per liter. A blood test determines leukopenia.

Treatment and therapy. In the twenty-first century, white blood cell transfusions are not a treatment option, primarily because of the abbreviated life span of a leukocyte, which is estimated to be between twenty-four and forty-eight hours. Most patients with leukopenia receive hematopoietic growth factors, such as filgrastim (Neupoegen), pegfilgrastim (Neulasta), or sargramostim (Leukine) to increase the number of circulating white blood cells.

Prognosis, prevention, and outcomes. Hematopoietic growth factors are the standard treatment for severe leukopenia at many cancer centers and can rapidly, within hours in some cases, increase leukocyte counts. Left untreated, the patient is at risk for severe and possibly life-threatening infections.


Bibliography

Ammann, Roland A., et al. "Exploring the Association of Hemoglobin Level and Adverse Events in Children with Cancer Presenting with Fever in Neutropenia." PLoS ONE, vol. 9, no. 7, 2014, pp. 1–8, doi:10.1371/journal.pone.0101696. Accessed 15 Oct. 2025.

Belok, Samuel H., et al. "Evaluation of Leukopenia During Sepsis as a Marker of Sepsis-defining Organ Dysfunction." PLoS One, vol. 16, no. 6, 2021, doi:10.1371/journal.pone.0252206. Accessed 15 Oct. 2025.

"Low Blood Cell Counts: Side Effect of Cancer Treatment." Mayo Clinic, 17 Sept. 2024, www.mayoclinic.org/diseases-conditions/cancer/in-depth/cancer-treatment/art-20046192. Accessed 15 Oct. 2025.

"Low White Blood Cell Count (Leukopenia)." Cleveland Clinic, 27 Oct. 2022, my.clevelandclinic.org/health/diseases/17706-low-white-blood-cell-count. Accessed 15 Oct. 2025.

Raval, Amit D., et al. "Burden of Neutropenia and Leukopenia Among Adult Kidney Transplant Recipients: A Systematic Literature Review of Observational Studies." Transplant Infectious Disease, vol. 25, no. 1, 2023, doi:10.1111/tid.14000. Accessed 15 Oct. 2025.

Shiozawa, Yusuke, et al. "Prognostic Significance of Leukopenia in Childhood Acute Lymphoblastic Leukemia." Oncology Letters, vol. 7, no. 4, 2014, pp. 1169–74, doi:10.3892/ol.2014.1822. Accessed 15 Oct. 2025.

Soliman, Megan, and Yamini Ranchod. “Leukopenia: Types, Symptoms, Causes, Treatment & More.” Healthline, 2 Oct. 2023, www.healthline.com/health/leukopenia. Accessed 15 Oct. 2025.

Full Article

  • ALSO KNOWN AS: Neutropenia, low white blood cell count, leucopenia
  • RELATED CONDITIONS: Neutropenia, a type of leukopenia

DEFINITION: Leukopenia is an abnormally low number of white blood cells, or leukocytes. The laboratory standard measurement of leukocytes ranges from approximately 4.0 to 11.0 × 109 cells per liter of blood.

Risk factors. Leukopenia may be related to the use of certain drugs (such as barbiturates and chemotherapeutics), radiation therapy, bone marrow or stem cell transplant, severe infections, or bone marrow diseases such as leukemia, myelodysplastic syndromes, acquired immunodeficiency syndrome (AIDS), aplastic anemia, or lupus. Patients older than seventy and those with comorbid diseases, such as diabetes, are at great risk for leukopenia during chemotherapy.

Etiology and the disease process. Chemotherapy and radiation therapy for cancer target the rapidly dividing cancer cells and other rapidly dividing cells, that is, hematopoietic stem cells. It takes about ten days for a new leukocyte to differentiate and mature from a hematopoietic stem cell, meaning that a patient receiving chemotherapy or radiation therapy can have fewer leukocytes for days. The role of leukocytes is to safeguard against infection by destroying bacteria. Leukopenia and its associated impaired immunity make a patient more susceptible to infections and may lead to septicemia. Untreated leukopenia may require hospitalization and use of intravenous anti-infective drugs.

Incidence. Most patients receiving chemotherapy, radiation therapy, or a bone marrow transplant experience leukopenia, which often delays chemotherapy.

Symptoms. Symptoms include recurrent infections, high-grade fever and chills, sore throat, cough, mouth ulcers, light-headedness, and diarrhea.

Screening and diagnosis. Leukopenia is defined as a leukocyte count less than approximately 4.0 × 109 per liter. Mild leukopenia is defined as a leukocyte count of 1.0 to 2.0 × 109 per liter, and severe leukopenia is defined as a leukocyte count of less than 0.5 × 109 per liter. A blood test determines leukopenia.

Treatment and therapy. In the twenty-first century, white blood cell transfusions are not a treatment option, primarily because of the abbreviated life span of a leukocyte, which is estimated to be between twenty-four and forty-eight hours. Most patients with leukopenia receive hematopoietic growth factors, such as filgrastim (Neupoegen), pegfilgrastim (Neulasta), or sargramostim (Leukine) to increase the number of circulating white blood cells.

Prognosis, prevention, and outcomes. Hematopoietic growth factors are the standard treatment for severe leukopenia at many cancer centers and can rapidly, within hours in some cases, increase leukocyte counts. Left untreated, the patient is at risk for severe and possibly life-threatening infections.


Bibliography

Ammann, Roland A., et al. "Exploring the Association of Hemoglobin Level and Adverse Events in Children with Cancer Presenting with Fever in Neutropenia." PLoS ONE, vol. 9, no. 7, 2014, pp. 1–8, doi:10.1371/journal.pone.0101696. Accessed 15 Oct. 2025.

Belok, Samuel H., et al. "Evaluation of Leukopenia During Sepsis as a Marker of Sepsis-defining Organ Dysfunction." PLoS One, vol. 16, no. 6, 2021, doi:10.1371/journal.pone.0252206. Accessed 15 Oct. 2025.

"Low Blood Cell Counts: Side Effect of Cancer Treatment." Mayo Clinic, 17 Sept. 2024, www.mayoclinic.org/diseases-conditions/cancer/in-depth/cancer-treatment/art-20046192. Accessed 15 Oct. 2025.

"Low White Blood Cell Count (Leukopenia)." Cleveland Clinic, 27 Oct. 2022, my.clevelandclinic.org/health/diseases/17706-low-white-blood-cell-count. Accessed 15 Oct. 2025.

Raval, Amit D., et al. "Burden of Neutropenia and Leukopenia Among Adult Kidney Transplant Recipients: A Systematic Literature Review of Observational Studies." Transplant Infectious Disease, vol. 25, no. 1, 2023, doi:10.1111/tid.14000. Accessed 15 Oct. 2025.

Shiozawa, Yusuke, et al. "Prognostic Significance of Leukopenia in Childhood Acute Lymphoblastic Leukemia." Oncology Letters, vol. 7, no. 4, 2014, pp. 1169–74, doi:10.3892/ol.2014.1822. Accessed 15 Oct. 2025.

Soliman, Megan, and Yamini Ranchod. “Leukopenia: Types, Symptoms, Causes, Treatment & More.” Healthline, 2 Oct. 2023, www.healthline.com/health/leukopenia. Accessed 15 Oct. 2025.

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