From the Guidelines
Reactive leukocytosis is a temporary and benign increase in white blood cell count in response to various physiological or pathological stimuli, distinct from leukocytosis associated with hematological malignancies like leukemia, as discussed in the context of hyperleukocytosis management 1. Reactive leukocytosis occurs as a normal immune response to conditions such as infections, inflammation, stress, or tissue damage, representing the body's natural defense mechanism.
- Key characteristics of reactive leukocytosis include:
- A temporary increase in white blood cell count
- Neutrophils are typically the predominant cell type increased
- The elevation in white blood cells is a response to an underlying condition rather than a primary blood disorder
- Common triggers include bacterial infections, viral illnesses, physical or emotional stress, surgery, trauma, burns, and certain medications
- It is crucial to distinguish reactive leukocytosis from pathological conditions like leukemia, where the elevated white blood cell count is due to abnormal cell production in the bone marrow, as seen in discussions around hyperleukocytosis and its management with therapies such as hydroxyurea 1. The diagnosis of reactive leukocytosis involves considering the clinical context, examining the peripheral blood smear, and evaluating other laboratory findings to rule out more serious hematological disorders.
- The management of reactive leukocytosis focuses on addressing the underlying cause, with the white blood cell count typically returning to normal once the condition resolves. In contrast to the management of hyperleukocytosis in leukemia, where interventions like leukapheresis or specific medications to lower the white blood cell count are considered 1, reactive leukocytosis does not require such aggressive interventions.
From the Research
Definition of Reactive Leukocytosis
- Reactive leukocytosis refers to an increase in the number of white blood cells (leukocytes) in response to a non-malignant condition, such as infection, inflammation, or physical stress 2, 3.
- This condition is characterized by an elevated white blood cell count, which can be caused by various factors, including:
- Infections, such as bacterial or viral infections
- Inflammatory processes, such as trauma or surgery
- Physical stress, such as seizures or overexertion
- Emotional stress
- Certain medications, such as corticosteroids, lithium, or beta agonists
Causes and Characteristics
- Reactive leukocytosis can be caused by a variety of factors, including:
- Infections, which can lead to an increase in neutrophils, a type of white blood cell 3
- Inflammatory processes, which can lead to an increase in eosinophils or basophils, other types of white blood cells 2
- Physical stress, which can lead to an increase in neutrophils and a shift to the left, indicating the presence of immature white blood cells 4
- The characteristics of reactive leukocytosis include:
- An elevated white blood cell count, which can range from mild to severe
- A shift to the left, indicating the presence of immature white blood cells
- The presence of toxic granulations, which can indicate infection or inflammation
Clinical Significance
- Reactive leukocytosis can be a predictor of non-infective mortality and morbidity, particularly due to cardiovascular or cerebrovascular causes 5
- It can also be a sign of underlying inflammation or infection, which can lead to serious complications if left untreated 3
- In some cases, reactive leukocytosis can be a sign of a more serious underlying condition, such as a bone marrow disorder 2
- The management of reactive leukocytosis depends on the underlying cause and may involve treatment of the underlying condition, as well as supportive care to manage symptoms and prevent complications 6