What are the causes of Neutropenia (low neutrophil count)?

From the Guidelines

Neutropenia is primarily caused by decreased production of neutrophils in the bone marrow, increased destruction of neutrophils in the bloodstream, or excessive sequestration of neutrophils in the spleen or other tissues, with common specific causes including medications, infections, autoimmune disorders, congenital disorders, nutritional deficiencies, bone marrow disorders, and radiation exposure. The causes of neutropenia can be categorized into several key areas, including:

• Decreased production of neutrophils in the bone marrow, which can be due to various factors such as chemotherapy drugs like cyclophosphamide, doxorubicin, and methotrexate 1
• Increased destruction of neutrophils in the bloodstream, which can be caused by infections, autoimmune disorders, or other conditions 1
• Excessive sequestration of neutrophils in the spleen or other tissues, which can occur in certain diseases or conditions 1 Common specific causes of neutropenia include:
• Medications, particularly chemotherapy drugs, antibiotics, antipsychotics, and antithyroid drugs 1
• Infections, especially viral infections like HIV, hepatitis, or influenza 1
• Autoimmune disorders, such as lupus or rheumatoid arthritis 1
• Congenital disorders, like Kostmann syndrome or cyclic neutropenia 1
• Nutritional deficiencies, particularly vitamin B12 or folate deficiency 1
• Bone marrow disorders, including leukemia, myelodysplastic syndrome, and aplastic anemia 1
• Radiation exposure 1 The underlying mechanism of neutropenia typically involves interference with the normal production and maturation of neutrophils in the bone marrow or increased peripheral destruction through immune-mediated processes 1. Treatment of neutropenia depends on identifying and addressing the underlying cause, with severe cases requiring granulocyte colony-stimulating factors like filgrastim (5-10 μg/kg/day subcutaneously) to stimulate neutrophil production 1.

From the FDA Drug Label

ADVERSE REACTIONS: Blood Dyscrasias The most serious adverse effect of chloramphenicol is bone marrow depression. Serious and fatal blood dyscrasias (aplastic anemia, hypoplastic anemia, thrombocytopenia, and granulocytopenia) are known to occur after the administration of chloramphenicol A reversible type of bone marrow depression, which is dose related, may occur. This type of marrow depression is characterized by vacuolization of the erythroid cells, reduction of reticulocytes and leukopenia, and responds promptly to the withdrawal of chloramphenicol

The causes of Neutropenia (low neutrophil count) include:

• Bone marrow depression caused by chloramphenicol, which can lead to granulocytopenia (a type of blood dyscrasia) 2
• Reversible bone marrow depression, which is dose-related and can cause leukopenia (reduction of white blood cells, including neutrophils) 2

From the Research

Causes of Neutropenia

The causes of neutropenia, a condition characterized by a low neutrophil count, can be diverse and include:

• Drugs, with certain medications such as metamizole, dipyrone, diclofenac, and ticlopidine being commonly associated with neutropenia 3, 4
• Infections, which can lead to acute neutropenia 3
• Autoimmune disorders, where the body's immune system attacks its own neutrophils 3, 4
• Congenital conditions, such as congenital neutropenia 3
• Chemotherapy and radiotherapy, which can suppress bone marrow function and lead to neutropenia 5, 6
• Hematological disorders, such as leukemia or lymphoma 5
• Idiopathic neutropenia, where the cause is unknown 3

Drug-Induced Neutropenia

Drug-induced neutropenia is a significant cause of neutropenia, with various medications being implicated, including:

• Non-chemotherapy drugs, such as antibiotics and anti-inflammatory agents 4, 6
• Chemotherapy drugs, which can cause neutropenia as a side effect 5, 6
• The use of granulocyte colony-stimulating factor (G-CSF) can help mitigate the risk of neutropenia associated with certain drugs 5, 6

Infection-Related Neutropenia

Infections can also lead to neutropenia, particularly in patients with compromised immune systems, such as those with autoimmune disorders or undergoing chemotherapy 3, 7

• Gram-negative bacilli, such as E. coli and Pseudomonas, are common causes of infection in neutropenic patients 7, 6
• Fungal infections, such as Candida and Aspergillus, can also occur in neutropenic patients 6