From the Guidelines
Leukocytosis is most commonly caused by infection, inflammation, or other conditions that stimulate the bone marrow to produce more white blood cells, as seen in various studies including 1. To address leukocytosis:
- Identify and treat the underlying cause, which may include bacterial infections, viral infections, or inflammatory conditions.
- Perform a complete blood count (CBC) with differential to determine which type of white blood cells are elevated.
- Additional tests may be necessary based on symptoms and clinical presentation. Common causes of leukocytosis include:
- Bacterial infections
- Viral infections
- Inflammatory conditions
- Leukemia or other blood disorders, as discussed in 1 and 1. The most recent and highest quality study, 1, suggests that leukocytosis can be a sign of primary myelofibrosis (PMF) or other myeloproliferative neoplasms, and recommends careful evaluation and management of these conditions. Monitor white blood cell counts regularly until they return to normal levels. If leukocytosis persists or worsens despite treatment, further investigation may be necessary to rule out more serious conditions. Leukocytosis occurs because the bone marrow increases production of white blood cells in response to various stimuli, such as infection or inflammation, as noted in 1. This is a normal physiological response aimed at protecting the body from harmful pathogens or repairing damaged tissues. Key points to consider in the management of leukocytosis include:
- Identifying and treating the underlying cause
- Monitoring white blood cell counts regularly
- Performing additional tests as necessary to determine the cause of leukocytosis
- Considering the possibility of more serious conditions, such as leukemia or other blood disorders, as discussed in 1 and 1.
From the FDA Drug Label
Infections and infestations ... Less frequently reported (<1%) were ... fever or chills. Investigations ... Other rarely observed adverse reactions (<0. 1%) include ... leukocytosis
- Leukocytosis is listed as a rarely observed adverse reaction, but the cause is not explicitly stated in the drug label. The FDA drug label does not answer the question.
From the Research
Causes of Leukocytosis
- Infections and chronic inflammatory conditions are common causes of secondary leukocytosis 2, 3, 4
- Physical stress, such as seizures, anesthesia, or overexertion, and emotional stress can also elevate white blood cell counts 2, 4
- Medications commonly associated with leukocytosis include corticosteroids, lithium, and beta agonists 2
- Increased eosinophil or basophil counts, resulting from a variety of infections, allergic reactions, and other causes, can lead to leukocytosis in some patients 2, 4, 5
- Primary bone marrow disorders, such as acute leukemias, chronic leukemias, and myeloproliferative disorders, can also cause leukocytosis 2, 3, 6
Malignant Causes of Leukocytosis
- Acute leukemias are more likely to present with severe symptoms and require urgent referral to a hematology subspecialist 3
- Chronic leukemias usually present with less severe symptoms and are often diagnosed incidentally due to abnormal blood cell counts 3
- Myeloproliferative disorders are a type of malignant cause of leukocytosis 6
Non-Malignant Causes of Leukocytosis
- Infectious conditions, such as bacterial infections, can cause leukocytosis 4
- Inflammatory conditions, such as autoimmune disorders, can also cause leukocytosis 6, 4
- Allergic reactions can cause increased eosinophil counts, leading to leukocytosis 2, 4
- Certain medications, such as corticosteroids, can cause leukocytosis 2
- Stressors, such as surgery, exercise, trauma, and emotional stress, can cause an acute leukocytosis 4