What is Leukocytosis (Elevated White Blood Cell Count)?
Leukocytosis refers to an increase in white blood cells, considered normal for one’s age. In adults, the white blood cell count is usually considered high if it exceeds 11,000 cells/µL, and is called hyperleukocytosis if it’s above 100,000 cells/µL. However, the definition of “high” could differ depending on one’s age and pregnancy status. For example, a count of 30,000 cells/µL may be unusual for adults, but normal for newborns.
Leukocytosis can be caused by different factors and can be categorized depending on which type of white blood cell is increased. This could include types of cells such as lymphocytes, neutrophils, eosinophils, basophils, monocytes, or immature cells called blasts. Common causes of leukocytosis include infections, inflammation, allergies, cancer, and inherited disorders. Looking at changes in the types of white blood cells can help pinpoint the cause. For instance, an increase in eosinophils could signal an allergy or parasite, while an increase in lymphocytes could be seen in people with viral illnesses, autoimmune diseases, and hyperthyroidism.
Further tests may depend on how the patient is feeling, how long they’ve had symptoms, changes in blood test results over time, the types of white blood cells present, and information from a complete blood count. In some cases, particularly when cancer is suspected, tests may include a bone marrow biopsy, flow cytometry, and genetic testing. The choice of treatment then depends on what underlying condition is causing the leukocytosis. While many people with this condition don’t need treatment, serious cases such as hyperleukocytosis and leukostasis need immediate medical intervention.
What Causes Leukocytosis (Elevated White Blood Cell Count)?
In your bone marrow, stem cells mature into different types of cells. Some become platelet-producing megakaryocytes, which are important for clotting blood. Others become red blood cells, which carry oxygen throughout the body. They also become various types of white blood cells such as eosinophils, basophils, neutrophils, monocytes and B or T lymphocytes, which play a crucial role in our immune response. When any of these white blood cell counts increase, it’s a condition known as leukocytosis.
Neutrophilia is named when there’s an increase in neutrophils, eosinophilia for an increase in eosinophils, basophilia for an increase in basophils, monocytosis for an increase in monocytes, and lymphocytosis for an increase in lymphocytes. Typically, neutrophilia is the most common cause of leukocytosis and can be caused by a variety of factors from bacterial infections, stress, and certain medications, to obesity, smoking, stress and other chronic conditions.
A leukemoid reaction is a temporary, significant increase in white blood cell count. This condition could be due to some medications, certain types of cancer, or infections with specific bacteria. It is often mistaken for leukemia, but an evaluation of your health and additional laboratory testing can help confirm the correct diagnosis.
Leukoerythroblastosis is a sign of a disease where non-blood forming or abnormal cells replace normal bone marrow space. The condition is often linked to severe diseases like coronavirus or toxic damage and may have a poor prognosis.
Lymphocytosis, an increase in lymphocytes, happens usually in children due to the rapid development of the immune system. However, it can also be caused by reactions to allergic substances, leukemia, stress, and certain viral infections.
Eosinophilia is an increase in eosinophils, a type of white blood cell. The causes are numerous and include allergies, infections, certain drugs, and some immune disorders. The severity of this condition does not necessarily indicate its cause.
Monocytosis is an increase in monocytes and is often associated with chronic infections or inflammatory conditions like tuberculosis, malaria, and certain types of cancer. A recent study suggests that the number of monocytes could predict the outcome in emergency room situations.
Basophilia, which is an increase of basophils, is less common. Its causes may include blood disorders, allergic or inflammatory reactions, and certain infections. If basophilia persists, it might suggest an underlying cancer or blood disease.
Leukemia, a type of cancer that affects blood cells, can occur in adults spontaneously, or in children due to inherited or new genetic mutations. Some genetic syndromes come with a higher risk of multiple types of cancer, including leukemia.
Risk Factors and Frequency for Leukocytosis (Elevated White Blood Cell Count)
Leukocytosis, or a high white blood cell count, can happen for many reasons. This condition is also a sign that can show the risk of illness or death. For example, if someone suffers a heart or brain injury, a higher severity of leukocytosis is linked to more severe damage and possible outcomes. Research has shown that people who have a heart attack and have high WBC counts have a higher risk of death. Two studies show that there’s a 4.4% to 7.7% death rate for heart attack patients with a low WBC count, but a much higher 15.9% to 27.3% death rate for those with a high WBC count. Leukocytosis is also associated with high blood pressure, issues with handling sugar in the body, diabetes, and risk of death. Similarly, most people with an inherited blood disorder called sickle cell disease also have high WBC counts. This condition worsens their prognosis during an episode of blocked blood vessels.
A severe form of leukocytosis, called hyperleukocytosis, tends to happen in people with some types of blood cancer. It’s found in 20% of people with acute myeloid leukemia (AML) and 10% to 30% of people with acute lymphoblastic leukemia (ALL). Hyperleukocytosis is also found in many new cases of two other types of blood cancer – chronic lymphocytic leukemia (CLL) and chronic myeloid leukemia (CML). Finally, a severe drug reaction can cause leukocytosis. This reaction, known as DRESS, causes an increase in white blood cells and atypical lymphocytes and can be found in 30% to 70% of affected patients.
Signs and Symptoms of Leukocytosis (Elevated White Blood Cell Count)
Leukocytosis is a condition where there is an increased number of white blood cells in the body. To understand the cause of leukocytosis, doctors may ask patients about signs of infection, history of blood disorders like sickle cell disease, lifestyle habits such as smoking, periods of extreme stress, absence of the spleen, pregnancy, thyroid disorders, family history of leukocytosis or exposure to certain chemicals at work. They might also consider if the patient has had cancer, as those who had chemotherapy or radiation therapy are at higher risk of leukemia or lymphoma, which are cancers of the blood and lymphatic system.
Patients with a high number of eosinophils, a type of white blood cell, may have specific symptoms depending on the affected organ systems. Doctors might ask about history of asthma, allergies, autoimmune diseases, infections, exposure to certain medicines and family history. Symptoms seen in these patients can include itching, hives, swelling, and rash. If the lungs are affected, symptoms like nasal congestion, wheezing, cough, and chest congestion may be present. Symptoms of heart involvement include shortness of breath, chest pain, palpitations, and signs of heart failure. Symptoms of underlying cancers can include fevers, chills, night sweats, unintentional weight loss, fatigue, or easy bruising.
Very high white blood cell counts, nearing 100,000 cells/µL, require immediate evaluation for cancers like leukaemia or disorders where blood cells excessively proliferate. Symptoms to look for in these cases include breathlessness, anemia, paleness, abnormal bleeding, tiny purple spots on the skin, recurrent infections, and fatigue. Physical signs that doctors might check for include pallor, petechiae (tiny purple spots), bruises, fast heart rate, enlarged lymph nodes, and an enlarged spleen.
Hyperleukocytosis refers to an extreme increase in white blood cells, which can cause symptoms mostly affecting the brain and lungs, but might also affect the heart and kidneys. Patients often have fever, shortness of breath, low oxygen levels, and brain-related symptoms like changes in vision, headache, dizziness, ringing in the ears, difficulty walking, confusion, excessive sleepiness, and in severe cases, coma. Treatment of hyperleukocytosis depends on the specific type of blood cancer present.
Testing for Leukocytosis (Elevated White Blood Cell Count)
To accurately diagnose a condition, doctors collect a complete medical history, perform a detailed physical examination, identify risk factors and carefully interpret blood tests. Further tests like flow cytometric immunophenotyping, molecular and DNA tests, and bone marrow examination can help spot blood cancers.
The exact white blood cell count can vary between laboratories because of differences in what’s considered normal and the type of blood analyzer used. For accuracy, flagged blood samples are carefully examined through a peripheral blood smear. Certain proteins can falsely inflate the white blood cell count. A high white blood cell count can also affect other blood values.
Doctors measure white blood cells by collecting a peripheral blood smear through a routine blood draw. The normal range for white blood cells can vary depending on age and race. For instance, infants usually have a higher count than adults and neutrophils, a type of white blood cell, become more common than lymphocytes as people age. The normal values change from newborns to adults, and even pregnancy can influence the count. Interesting fact: People of African, Middle Eastern, and West Indian descent can have lower normal levels of white blood cells and neutrophils compared to those of Hispanic and European origin.
If a patient has high white blood cell counts, the first step is to get a differential white blood cell count and check any previous complete blood count tests for trends. If there is concern about cancer, the patient should be referred to a specialist in blood diseases and cancers.
If the number of neutrophils, a subset of white blood cells, is moderately high and stable in a patient showing no symptoms, ordering regular complete blood count tests as an outpatient might be suitable. However, patients with an extremely high count, or who are very sick with symptoms such as sudden high fever or serious pain in the abdomen, should be hospitalized and evaluated urgently. Additional testing could include kidney and liver function tests, inflammatory markers, and cultures to check for infection, among other tests.
There’s no specific level of lymphocytosis (high lymphocyte count) that demands emergency evaluation. However, patients with unstable vital signs or difficulties breathing need immediate assessment. Additional tests to consider include renal and liver function tests, inflammation markers, flow cytometry, bone marrow biopsy, viral panels, cultures, and possibly imaging depending on the suspected system involved.
For eosinophilia (high eosinophil count), the severity of the illness, not the actual eosinophil count, determines the need for emergency evaluation. Additional possible tests could include allergy testing, ova and parasite tests, and heart-related tests among others.
In case of basophilia (high basophil count) and monocytosis (high monocyte count), peripheral smear is the first step of evaluation. Depending on the outcome, further tests could include bone marrow aspiration and biopsy, DNA, and chromosomal analysis.
Hyperleukocytosis is when the white blood cell count is very high (100,000 cells/µL or higher). Patients may or may not have symptoms. Leukostasis, a condition with signs of tissue oxygen shortage, is diagnosed when a patient with hyperleukocytosis shows symptoms.
Treatment Options for Leukocytosis (Elevated White Blood Cell Count)
Treatment for a high white blood cell count, or leukocytosis, is often tailored to the specific cause. Many people with this condition don’t require treatment at all. Some just need to have regular blood tests to keep an eye on their white blood cell count. Others might need treatment for things like infections, autoimmune diseases, hormone disorders, or cancer.
In severe cases, the high white blood cell count can become an emergency situation if the individual starts showing symptoms or signs that not enough oxygen is reaching the body’s tissues. This problem, known as leukostasis, is most often seen with a type of blood cancer called acute myeloid leukemia (AML), but it can occasionally happen with chronic lymphocytic leukemia (CLL) and acute lymphoblastic leukemia (ALL). To manage leukostasis and prevent further health decline, doctors may use treatments such as chemotherapy, a procedure called leukapheresis that filters the blood, and certain medications.
Patients with a particularly high white blood cell count also have a higher risk of developing a condition called disseminated intravascular coagulation, where the body’s normal blood clotting process becomes overactive. This is due to an increase in the formation of a protein needed for blood clotting called thrombin and an excessive breakdown of another clotting protein called fibrin. In such cases, doctors will keep a close eye on the patient’s clotting ability, replenish the levels of a different clotting protein called fibrinogen, and give the patient a transfusion of platelets, which are the blood cells responsible for clotting, as necessary.
What else can Leukocytosis (Elevated White Blood Cell Count) be?
If you have high white blood cell count, known as leukocytosis, there could be many reasons behind it. Your doctor needs to determine whether it’s a sudden (acute) or long-term (chronic) case and investigate how high your count is. If it’s very high, this could be due to severe sickness or even cancer.
The reasons for a sudden rise in white blood cells can include:
- A severe body reaction to an illness or condition
- An infection
- Severe allergies
- Lack of oxygen in your tissues
- Certain medications, like epinephrine, corticosteroids, NSAIDs, specific antibiotics, epilepsy drugs, beta-agonists, allopurinol, penicillin, opioids, and metformin.
- After having a vaccine
- A heart attack
- Heavy bleeding or ruptured blood cells
Also, a few conditions or situations, like sepsis, severe systemic response to an infection, or pregnancy, can cause an acute rise in white blood cells.
Reasons behind a long-term high white blood cell count can be:
- Smoking or obesity
- Persistent allergies
- Autoimmune disorders
- Vasculitis, inflammation of blood vessels
- Connective tissue disorders
- Cancer
- Chronic infections or pregnancy
- Absence of a spleen
- Certain genetic conditions
Your healthcare provider will consider all these possibilities when trying to figure out the cause behind your leukocytosis.
What to expect with Leukocytosis (Elevated White Blood Cell Count)
When leukocytosis (an increased white blood cell count) is due to benign, non-cancerous, and treatable conditions, the outlook is usually good. But if it’s caused by cancerous conditions like lymphomas, the prognosis isn’t as positive. Factors that contribute to survival include age, existing health conditions, prior history of certain blood disorders, exposure to harmful chemicals or radiation, and particular genetic and cellular features. Patients with a very high white blood cell count (over 35,000 cells per micro-liter) typically have a poor prognosis.
An elevated white blood cell count can also serve as a marker for inflammation, and can help predict outcomes in patients without an infection. Patients with a high white blood cell count who have had a heart attack or stroke or who are in the intensive care unit are likely to have more health problems and a higher risk of death. Studies also show a link between a high white blood cell count and worsening blood sugar control, along with reduced insulin sensitivity.
Possible Complications When Diagnosed with Leukocytosis (Elevated White Blood Cell Count)
Having a high white blood cell count, or leukocytosis, can cause problems beyond just diagnosing a disease. In extreme cases, having too many white blood cells can injure tissues due to inflammation, which can hurt the function of your organs, and may lead to serious problems like sepsis or organ failure. It’s important to find and address the cause of the high white blood cell count quickly to prevent any more issues from happening.
There are some health issues that may occur specifically if hyperleukocytosis (an extremely high white blood cell count) is present:
- Myocardial ischemia (reduced blood flow to the heart)
- Overload in the right side of your heart
- Kidney function issues (renal insufficiency)
- Priapism (a long-lasting erection that can hurt)
- Acute limb ischemia (sudden lack of blood flow to a limb)
- Tissue damage in the intestines (bowel infarction)
- Falling into a coma
- Respiratory failure
- A harmful blood clotting issue (disseminated intravascular coagulation)
- Bleeding inside the skull (intracranial hemorrhage)
- Tumor lysis syndrome (a rapid release of cells into the bloodstream)
This rapid release of cells into the bloodstream can also lead to tumor lysis syndrome, which can cause its own problems, including:
- The levels of potassium, phosphorus, and calcium in your blood getting out of balance, leading to heart failure, arrhythmias, seizures, muscle cramps, twitching, fainting, and in extreme cases even sudden death
- Too much uric acid in your blood (hyperuricemia)
- Acute kidney failure
Preventing Leukocytosis (Elevated White Blood Cell Count)
Leukocytosis, or a high white blood cell count, can occur due to a range of factors. Causes include infections, certain types of medication, stress, or serious illnesses like leukemia or lymphoma. It’s important for patients and doctors to understand what might cause leukocytosis and how it could impact health.
Patients need to be aware of the importance of seeking medical help if they experience symptoms such as a fever, feeling tired all the time, unexplained weight loss, or getting infections often. These symptoms could be a sign of an underlying health problem that needs quick examination and treatment.
Patients also need to know the importance of reviewing their medication regimen regularly and openly discussing any recent changes or additions with their doctors. Some medications can cause leukocytosis, so it’s important to keep healthcare professionals informed about any changes to medications.
Patients, especially those with long-term health conditions or a history of blood disorders, should also understand the importance of regular health checks and monitoring. Regular health exams can help detect and manage concerns related to leukocytosis early on.
By raising awareness and encouraging active involvement in health care, patients and healthcare professionals can effectively respond to risks associated with leukocytosis and intervene promptly if necessary.