What to Know About Granulocytosis (2024)

Granulocytes are a type of white blood cell that appear granular when viewed under a microscope. Immature granulocytes (IGs) develop in the bone marrow, where they give rise to neutrophils, eosinophils, and basophils.

Low levels of mature granulocytes may suggest a health issue that may be serious. High IG counts suggest an infection or may point to a bone marrow condition. Most healthy people don't have immature granulocytes in their blood, so low IG levels aren't a cause for concern.

This article will help you to understand granulocytes and what low or high levels can mean. It also explains the conditions associated with high or low granulocytes, and how they are diagnosed and treated.

Types of Granulocytes

Granulocytes are produced in the bone marrow. They all come from the same precursor, called an immature granulocyte. They differentiate as they mature and prepare to fight disease. The specific roles of these mature cells include:

• Neutrophils:The most common type of white blood cell, neutrophils help with tissue healing and fighting infections, especially bacterial infections.
• Eosinophils: Eosinophils are associated with allergies, parasitic infections, and cancer.
• Basophils:Basophils are granulocytes that are involved with inflammation. They can release histamine, which causes a variety of responses, and heparin, which prevents blood from clotting.

Mast cells also arise from immature granulocytes. Mast cells recognize harmful infectious organisms and aid in releasing inflammatory chemicals to help boost the immune response.

Neutrophils are the most common granulocyte in your bloodstream, accounting for up to 60% of the white blood cells. When viewed under a microscope, they develop band-like features as they mature. These are sometimes referred to as band cells.

The mature neutrophils have a short lifespan but your body produces about 100 billion of them each day. Normal neutrophil levels are between 2,500 and 6,000 neutrophils per microliter of blood. It's when your body produces too many or too few that health conditions may be at work.

Eosinophils follow a similar pathway and survive for three to five days. Basophils, making up just 1% of your white blood cells, have a normal count of between 15 and 50 per cubic millimeters (mm3).

Immature Granulocytes

Immature granulocyte (IG) cells arise in the bone marrow. These cells undergo stages of development (as metamyelocytes, myelocytes, and promyelocytes) before becoming mature.

Low Levels

Low levels of mature granulocytes usually occur with an acquired condition, although there can be an underlying genetic condition in rare cases.

Since immature granulocytes aren't usually in the bloodstream for healthy people, healthcare providers will likely find low levels of mature granulocytes to be of greater concern.

Causes

Some of the conditions that cause low granulocytes may include:

• Autoimmune diseaseslikelupus
• Bone marrow diseases
• Chemotherapydrugs that kill cancer cells, or a cancer itself
• Infections liketuberculosis(infectious disease affecting the lungs)
• Vitamin deficiencies
• Certain medications

Toxic exposures, such as those to lead or mercury, also can lead to low levels.

Symptoms

The symptoms of low granulocyte levels may be similar to those of an infection. You may experience:

• Fever and chills
• Digestive tract pain (abdomen and rectum)
• Mouth infections
• Trouble breathing

You also may experience fatigue or dizziness, an increased heart rate, or a sudden drop in blood pressure.

Treatment

While the treatment for low granulocyte levels may vary depending on your situation (for example, if the condition is chemotherapy-related) there are some main strategies for healthcare providers. They include:

• Drugs to boost production of granulocytes in the bone marrow, such as Neupogen(filgrastim)
• Antibiotics to prevent or treat infection
• Bone marrow transplant to assist the production of granulocytes with healthy donor tissue

Treatment also may include lifestyle changes to help you avoid infection, like wearing a face mask in public or avoiding crowds.

High Levels

Mature granulocyte levels often increase with illness or infection, but the presence of immature granulocytes (IGs) in your blood samples will raise suspicion of an underlying health problem, too.

Healthcare providers may be concerned when the level of immature granulocytes reaches or exceeds a normal level of 1% of your total white blood cell count. At 2%, the level is considered high.

Causes

Causes of high IG levels, as well as high levels of mature granulocytes, often include infection and allergic reaction, but they also point to bone marrow disorders, blood-related cancer, and more. These causes of increased granulocytes include:

• Inflammatory diseases such as vasculitis, affecting the blood vessels
• Viral or bacterial infections, such as tuberculosis
• Sepsis, a severe reaction to a blood infection)
• Autoimmune diseases, such as rheumatoid arthritis
• Bone marrow disorders
• Cancer

The presence of elevated IG levels is a useful finding to help your healthcare provider with making a diagnosis.

Symptoms

Some medical conditions can cause granulocytes to increase. This can cause symptoms such as:

• Swelling
• Pain
• Fatigue
• Fever

However, certain medical issues can cause specific symptoms. Examples include:

• Tuberculosis, with a cough, hemoptysis (coughing blood), chest pain, and a fever
• Vasculitis and fever, as well as an area of swelling, redness, and tenderness. This may develop on the leg or other areas of the body.
• Medication use that leads to bleeding, increased risk of infections, and symptoms of anemia

Treatment

Treatment for high levels of granulocytes can include antibiotics to prevent or treat infection. It also may include allergy medication. When these high levels help to reveal a cancer diagnosis, treatments may include chemotherapy, radiation, and other cancer care.

Diagnosis

Granulocytosis is diagnosed with a blood test called a complete blood count (CBC). This test measures different types of blood cells, including white blood cells, red blood cells, platelets, and some other characteristics of blood, such as hemoglobin and hematocrit (the ratio of red blood cells to other blood elements by volume).

Granulocytes are measured as the number of cells per cubic millimeter and as a percentage of total leukocytes (white blood cells). Lymphocytes are a type of leukocyte, and granulocytes are a type of leukocyte. Standard values may vary from one lab to another, but the values below are widely accepted.