The immune system is a complex network of cells, tissues, and organs that protects the body from foreign invaders and injury. White blood cells (WBCs), also called leukocytes, act like the body's security guards and defense troops, acting to identify, target, and eliminate harmful invaders that threaten the body's health and integrity.
Therefore, a high WBC count can be a sign that something is awry. Doctors measure WBCs as a simple and inexpensive way to screen for, diagnose, and monitor a range of conditions, including infection, inflammation, and other immune system disorders.
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What Is Considered a High White Blood Cell Count?
Normal blood counts fall within a range established by collecting and analyzing data from a large, healthy population to determine the typical variation in measurement. This is called a reference range.
A white blood cell count is a test that measures the total number of WBCs in the body. The normal range for WBC counts is between 4,000 and 11,000 cells per microliter (cells/µL) of blood. A WBC count exceeding 11,000 cells/µL is considered high and diagnostic for leukocytosis (high white blood cells).
It is normal for reference ranges to vary slightly depending on the lab and the patient's sex and age. In young children, for example, the upper limit of the normal range is higher than in adults. A WBC count as high as 17,000 cells/µL and 30,000 cells/µL would be considered normal for children younger than two and newborns, respectively. (50)
What Does a High White Blood Cell Count Mean?
Temporary increases in WBC count can occur as part of a normal physiologic immune response to acute infections, stress, or injury. This is called reactive leukocytosis. Chronically high WBC counts might indicate chronic inflammatory conditions or abnormal cell production (such as in blood cancers). (68)
There are five main types of WBCs:
A high total WBC count can result from an increase in one type of white blood cell or from elevations in multiple types of white blood cells (50).
A high WBC count alone usually doesn't cause symptoms, but the underlying condition that is causing it can. Patients with leukocytosis may complain of the following symptoms:
What Causes High White Blood Cell Count?
A high WBC count can be caused by a variety of underlying factors, including:
- Autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), or Crohn's disease
- Cavities
- Environmental and food allergies
- Heart attack
- Infection (caused by bacteria, viruses, fungus, or parasites)
- Medications, most commonly including corticosteroids, lithium, and beta-agonists (e.g., albuterol)
- Obesity
- Physical and emotional stress
- Pregnancy
- Recent vaccination
- Smoking
- Surgical removal of the spleen (splenectomy)
- Thyroid disease (32, 68)
What Cancer Causes High White Blood Cell Count?
White blood cells are made through a process called hematopoiesis, which occurs in the bone marrow. Stem cells in the bone marrow differentiate and specialize into the different types of white blood cells. Once WBCs have matured in the bone marrow, they enter the bloodstream to perform their roles in immune responses. Leukocytosis, especially when cell counts are greater than 100,000 cells/µL, can be a symptom of certain blood cancers or bone marrow disorders that cause uncontrolled proliferation of WBCs.
Leukemia is a type of cancer that originates in the bone marrow and results in the overproduction of abnormal white blood cells. The disease can be classified into various subtypes based on the speed of progression (acute or chronic) and the type of white blood cell affected (lymphoid or myeloid). The four main types of leukemia are acute lymphocytic leukemia (ALL), acute myelogenous leukemia (AML), chronic lymphocytic leukemia (CLL), and chronic myelogenous leukemia (CML).
Lymphoma is a type of cancer that originates in the lymphatic system and affects lymphocytes. The two main types of lymphoma are Hodgkin lymphoma and non-Hodgkin lymphoma.
Warning signs that may indicate a high WBC count is being caused by cancer include:
- Fever of unknown origin
- Unintentional weight loss
- Night sweats
- Easy bruising
Lab Tests for High White Blood Cell Count
A complete blood count (CBC) is the primary test to measure the number of white blood cells in the blood. This test provides a detailed overview of the different types of blood cells, including red blood cells, white blood cells, and platelets. It helps in diagnosing various conditions that affect blood cell production and function.
- Order a CBC through Access Med Labs
A WBC differential is often included with a CBC (CBC with diff). It breaks down the total WBC count into its different cellular components: neutrophils, lymphocytes, basophils, eosinophils, and monocytes. Each type of WBC has specific roles in the immune system, and their relative proportions can provide clues about underlying health conditions.
- Order a CBC with differential through Access Med Labs
A peripheral blood smear involves spreading blood on a microscope slide and staining it to visualize the blood cells. This test allows for a detailed examination of white blood cells' size, shape, and appearance, helping to identify abnormalities that may indicate specific diseases.
For example:
- Toxic granulation (an increase in staining density within neutrophils): acute infection and inflammation
- Howell-Jolly bodies (small remnants inside cells that stain purple): splenectomy
- Blast cells (immature WBCs): acute leukemia
- Auer rods (pink or red-stained needle-shaped structures): myelogenous leukemia
Additional Testing and Biomarkers
Additional tests to evaluate for or confirm suspected causes of leukocytosis should be guided by clinical context. Reasonable testing options to consider include:
- Blood, urine, or joint cultures to rule out infection
- Viral titers (e.g., Epstein Barr virus)
- Liver function tests
- Inflammation markers (e.g., erythrocyte sedimentation rate and C-reactive protein)
- Ova & parasite stool test
- Antinuclear antibodies
- Chest x-ray
When blood cancers or bone marrow disorders are suspected, confirmatory testing should include:
- Flow cytometry analyzes the physical and chemical characteristics of cells. It can help predict how aggressive the cancer is and how it will respond to treatment.
- A bone marrow biopsy involves extracting a small sample of bone marrow tissue to diagnose bone marrow disorders.
- Cytogenetic analysis involves examining the chromosomes of cells to detect genetic abnormalities. This test can identify genetic changes associated with blood cancers, such as the genetic rearrangement between chromosomes 9 and 22 that can be observed in CML.
- Molecular testing identifies specific genetic mutations associated with certain diseases. For example, the BCR-ABL fusion gene is a hallmark of CML that can be detected using molecular techniques.
- Uric acid and lactate dehydrogenase, which are often elevated in leukemias and lymphomas (54)
- Imaging, including chest x-ray, ultrasound, computed tomography (CT), and positron emission tomography (PET), to detect tumor masses or bone marrow infiltration
Interpretation of Test Results
Lab results should always be interpreted in the context of the patient's overall health and clinical presentation. Doctors should exercise their due diligence in repeating a CBC to confirm laboratory findings and order follow-up testing to investigate further.
Close monitoring will help differentiate between acute and chronic causes of leukocytosis.
The following chart outlines common causes of elevations in certain WBC types to help narrow the reasons why a patient presents with leukocytosis:
Management and Treatment Options
The primary approach to managing high WBC counts is to treat the underlying cause. Examples include:
- Antibiotics or antimicrobial herbs for bacterial infections
- Trigger avoidance and antihistamines for allergies
- Anti-inflammatory herbs and diet to reduce inflammation
- Stress management techniques for emotional stress
- Conventional (e.g., chemotherapy, radiation, stem cell transplants) and complementary medicine for cancer
Leukapheresis is a medical procedure that quickly reduces a high WBC count. During this procedure, blood is taken from the patient, white blood cells are separated and removed, and the remaining blood components are returned to the patient. This treatment is often used in emergencies to manage extremely high WBC counts in conditions like leukemia, helping to reduce symptoms and prevent complications.
The following lifestyle practices play a role in supporting a healthy immune system:
- Eat a healthy, nutrient-dense diet low in processed foods and added sugars, such as the Mediterranean diet
- Don't smoke
- Practice good dental hygiene and stay up-to-date on routine dental exams
- Wash your hands frequently
- Exercise regularly (32, 42)
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Key Takeaways
- High white blood cell counts can indicate a variety of conditions, from acute infections to serious bone marrow disorders and blood cancers.
- The accurate diagnosis and effective treatment of leukocytosis rely on a comprehensive approach that includes lab testing and ongoing monitoring.
- Patients are encouraged to stay informed and proactive about their health by seeking guidance from healthcare providers to manage high WBC counts, ensuring timely and appropriate care.
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