Neutropenia describes a condition where an individual has a lower-than-normal level of neutrophils in their blood. Neutrophils are a specific type of white blood cell produced in the bone marrow and play a role in the body’s immune defense. When these cells are in insufficient numbers, the body’s ability to combat infections is compromised.
Understanding Neutropenia
Neutrophils are a type of granulocyte that forms a significant part of the body’s initial immune response against infection and inflammation. They function by ingesting and destroying invading microorganisms such as bacteria and fungi. A healthy adult typically maintains an absolute neutrophil count (ANC) above 1,500 cells per microliter of blood.
Neutropenia is classified into categories based on the absolute neutrophil count. Mild neutropenia is diagnosed when the ANC falls between 1,000 and 1,500 cells per microliter. Moderate neutropenia ranges from 500 to 1,000 cells per microliter, while severe neutropenia is indicated by an ANC below 500 cells per microliter.
Causes of Neutropenia
Various factors can lead to neutropenia, often categorized by whether they affect neutrophil production, cause their destruction, or alter their distribution within the body. Problems originating in the bone marrow represent one broad category. These can include conditions like aplastic anemia, certain leukemias, or myelodysplastic syndromes.
Infections also cause neutropenia. Viral infections, such as influenza, measles, hepatitis (A, B, C), HIV, Epstein-Barr virus, and cytomegalovirus (CMV), can temporarily suppress bone marrow activity or lead to increased neutrophil destruction. Bacterial infections, including tuberculosis and sepsis, can also contribute to a reduced neutrophil count due to increased consumption.
Autoimmune disorders, where the body’s immune system mistakenly attacks its own healthy cells, can target and destroy neutrophils. Examples include lupus and rheumatoid arthritis. Certain medications are another common cause, with chemotherapy drugs being a significant factor due to their impact on rapidly dividing cells, including those in the bone marrow. Other medications, such as some antibiotics, antiviral drugs, antithyroid medications, and certain psychiatric drugs, have also been linked to neutropenia.
Congenital conditions, which are present from birth, can also result in neutropenia. These are often linked to genetic mutations affecting neutrophil maturation. Examples include severe congenital neutropenia (Kostmann syndrome) and cyclic neutropenia, which involves regular fluctuations in neutrophil levels.
Symptoms and Risks
Neutropenia itself does not cause direct symptoms; rather, the reduction in neutrophils leads to an increased susceptibility to infections. The primary health risk associated with neutropenia is the heightened vulnerability to bacterial and fungal infections. Even common bacteria that a healthy immune system normally tolerates can cause serious illness when neutrophil counts are low.
Common signs of infection in a person with neutropenia include a fever, which is considered a medical emergency, as well as chills and sweating. Other indications include a sore throat, mouth sores or ulcers, swollen lymph nodes, or a rash at an infection site. Individuals might also experience symptoms related to specific infections, such as coughing or shortness of breath from pneumonia, diarrhea, or pain and burning during urination from a urinary tract infection.
These infections can be more severe or frequent because the body lacks its primary defense mechanism against invading pathogens. Without enough neutrophils to engulf and destroy bacteria and fungi, these microorganisms can multiply unchecked, potentially leading to widespread and life-threatening conditions like septic shock.
Diagnosis and Treatment Approaches
Diagnosing neutropenia begins with a complete blood count (CBC) test, which measures the levels of different blood cells, including neutrophils. This test provides the absolute neutrophil count (ANC), which helps to confirm the diagnosis and classify the severity of the condition. An ANC below 1,500 cells per microliter indicates neutropenia.
If neutropenia is confirmed and the underlying cause is not immediately apparent, further diagnostic tests may be performed. A bone marrow aspiration and biopsy can be conducted to examine the bone marrow’s ability to produce neutrophils and to rule out conditions such as bone marrow failure or malignancies. Additional tests may include checking for autoimmune markers, HIV, hepatitis viruses, or genetic mutations.
Treatment approaches for neutropenia focus on managing the underlying cause and preventing infections. If a medication is identified as the cause, discontinuing or adjusting the dose may resolve the neutropenia. For individuals with low neutrophil counts, particularly those undergoing chemotherapy, medications called granulocyte colony-stimulating factors (G-CSFs), such as filgrastim or pegfilgrastim, may be prescribed. These drugs stimulate the bone marrow to produce more neutrophils, helping to increase counts and reduce the risk of severe infections.
Infection prevention strategies are also important, including practicing good hand hygiene, avoiding crowded places, and promptly seeking medical attention for any signs of infection, especially fever. Prophylactic antibiotics may be used in certain high-risk situations to prevent bacterial infections. The specific treatment plan is individualized based on the cause, severity, and overall health of the person.