Leukocytosis: An Overview of Elevated Leukocyte Counts

Leukocytosis refers to a condition characterized by an increase in the number of leukocytes, commonly known as white blood cells (WBCs), in the blood. WBCs are crucial components of the immune system, responsible for defending the body against infection and disease. Assessing leukocyte levels is a routine part of a complete blood count (CBC), a common blood test used to evaluate overall health.

Types of Leukocytes and Their Functions

• Neutrophils: Primarily combat bacterial infections through phagocytosis.
• Lymphocytes: Include B cells (antibody production), T cells (cellular immunity), and natural killer (NK) cells (killing infected cells).
• Monocytes: Differentiate into macrophages and dendritic cells, involved in phagocytosis and antigen presentation.
• Eosinophils: Target parasites and are involved in allergic reactions.
• Basophils: Release histamine and other mediators involved in inflammation and allergic responses.

Causes of Leukocytosis

Physiological Factors

• Stress: Physical or emotional stress can trigger a temporary increase in WBCs.
• Exercise: Strenuous physical activity can elevate leukocyte counts.
• Pregnancy: WBC counts may increase during pregnancy, particularly in the later stages.
• Medications: Certain drugs, such as corticosteroids, can cause leukocytosis.

Pathological Conditions

• Infections: Bacterial, viral, fungal, and parasitic infections are common causes.
• Inflammation: Inflammatory conditions like arthritis, vasculitis, and inflammatory bowel disease can elevate WBC counts.
• Allergic Reactions: Severe allergic reactions can trigger an increase in eosinophils and basophils.
• Hematologic Disorders: Leukemia, myeloproliferative neoplasms, and other blood cancers can lead to abnormally quantities of WBCs.
• Tissue Damage: Trauma, burns, and surgery can cause a temporary increase.
• Splenectomy: Removal of the spleen can result in a sustained elevation of leukocytes.

Diagnostic Evaluation

When an elevated leukocyte count is detected, further investigation is typically warranted to determine the underlying cause. This may involve:

• Review of Medical History: Assessing past illnesses, medications, and other relevant factors.
• Physical Examination: Looking for signs of infection, inflammation, or other underlying conditions.
• Complete Blood Count (CBC) with Differential: Provides detailed information about the different types of WBCs.
• Blood Smear: Microscopic examination of blood cells to assess their morphology.
• Bone Marrow Biopsy: May be necessary to evaluate bone marrow function and rule out hematologic disorders.
• Imaging Studies: X-rays, CT scans, or MRIs may be used to identify infections or inflammatory processes.

Management and Treatment

Treatment depends on the underlying cause. For example:

• Infections: Antibiotics, antivirals, or antifungals may be prescribed.
• Inflammation: Anti-inflammatory medications or corticosteroids may be used.
• Hematologic Disorders: Chemotherapy, radiation therapy, or stem cell transplantation may be necessary.