Eosinophilia is a condition characterized by an increased number of eosinophils in the blood. It is typically identified through a complete blood count when levels rise above 500 eosinophils per µL of blood.
Eosinophilia most commonly develops as a response to parasitic infections or allergic reactions. However, in some cases it can also be associated with more serious conditions, such as lymphoma.
Eosinophils are immune cells that help defend the body against infectious agents. Although they play an important role in immune defense, they are normally present in smaller numbers in the bloodstream compared with other white blood cells.
Main symptoms
Eosinophilia usually does not cause noticeable signs or symptoms and is often discovered during a routine complete blood count that shows increased eosinophil levels.
However, depending on the underlying cause, symptoms such as abdominal swelling, diarrhea, nausea, vomiting, fatigue, or weight loss may occur, particularly in cases of intestinal parasite infections.
Reference values
Normal eosinophil reference values in the blood range from 20 to 500 eosinophils per µL of blood.
Values above 500/µL are considered eosinophilia.
How to confirm eosinophilia
Eosinophilia can be classified according to its severity:
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Mild eosinophilia: 500 to 1500 eosinophils per µL of blood
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Moderate eosinophilia: 1500 to 5000 eosinophils per µL of blood
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Severe eosinophilia: More than 5000 eosinophils per µL of blood
The absolute eosinophil count should be evaluated by a doctor along with other parameters from the complete blood count and additional laboratory tests to reach a diagnosis.
Relative eosinophilia
Relative eosinophilia refers to an increased proportion of eosinophils compared with the total leukocyte count in the leukogram and is expressed as a percentage (%).
In these cases, relative eosinophilia is defined as a value greater than 6%.
How to understand the result
The higher the number of eosinophils detected in a blood test, the more likely it is that an underlying condition is present.
However, the complete blood count must be evaluated together with other laboratory parameters requested by a doctor to reach a diagnosis and begin appropriate treatment.
If eosinophils are the only altered value on the test and no other abnormalities are found, the doctor may recommend repeating the test.
This helps determine whether eosinophilia persists. If it does not persist, the finding may not be clinically significant.
Main causes
The most common causes of eosinophilia include:
1. Parasitic infection
Parasitic infections such as ascariasis, hookworm infection, or strongyloidiasis are among the main causes of significant eosinophilia.
This often occurs when parasites pass through the lungs during part of their life cycle, which can lead to pulmonary infiltrates.
When this happens, Löffler syndrome may develop, causing symptoms such as dry cough and progressively worsening shortness of breath due to the accumulation of eosinophils in the lungs.
Also recommended: Symptoms of Parasites: 7 Signs (with Online Symptom Test) tuasaude.com/en/symptoms-of-pinwormsWhat to do: In addition to a complete blood count, doctors often recommend a stool parasite exam and a C-reactive protein (CRP) blood test.
A chest X-ray may also be ordered to check for pulmonary infiltrates.
If a parasitic infection is confirmed, treatment usually includes antiparasitic medications chosen according to the specific parasite causing the infection.
2. Allergies
Allergic conditions, including respiratory allergies such as asthma or allergic rhinitis, as well as contact, food, or medication allergies, can increase eosinophil levels in the blood.
In these situations, eosinophils release inflammatory substances into surrounding tissues in an attempt to combat the allergen responsible for the reaction.
What to do: Avoiding contact with the substance that triggers the allergy is important. Doctors may also recommend antihistamines or corticosteroids to help relieve symptoms.
Consulting an allergist can help identify the specific trigger and guide more targeted treatment.
In some cases, doctors may also request immunoglobulin E (IgE) testing. IgE is a protein normally found in small amounts in the blood but tends to increase in people with allergies.
3. Skin diseases
Certain skin conditions, such as pemphigus, granulomatous dermatitis, and eosinophilic fasciitis, may also lead to elevated eosinophil levels.
These conditions often cause red or white spots on the skin that may be scaly and may be associated with itching or pain.
What to do: A consultation with a dermatologist is recommended so the condition can be properly evaluated and treated.
4. Hodgkin lymphoma
Hodgkin lymphoma is a type of cancer that affects lymphocytes, which are key immune cells in the body.
This type of cancer causes symptoms such as swollen lymph nodes in the neck, unexplained weight loss, itching throughout the body, and persistent high fever.
In Hodgkin lymphoma, lymphocyte levels may decrease, a condition known as lymphopenia. As the body attempts to compensate for immune dysfunction, eosinophil production may increase, leading to eosinophilia.
What to do: Treatment should be guided by an oncologist and may include chemotherapy, targeted therapy, immunotherapy, or radiation therapy.
In some cases, a bone marrow transplant may be necessary to help restore normal blood cell production.