Definition

A total eosinophil count test is a blood test that measures the number of eosinophils, a type of white blood cell. Eosinophils are part of the immune system and are primarily involved in allergic responses and fighting parasitic infections such as worms. They also play a role in controlling infections and triggering inflammation during allergic reactions.

Inflammation caused by eosinophils can have both beneficial and harmful effects. It involves an immune response at the infection site but may also result in tissue damage in the surrounding area.

The results of a total eosinophil count may be reported as an absolute count or a percentage. This test is often performed as part of a complete blood count (CBC) along with other white blood cell analyses. Abnormal results, whether eosinophil levels are too high or too low, could indicate an underlying health condition.

Indications

Eosinophil tests are typically ordered if abnormalities are detected in a leukocyte type count test or if a specific condition is suspected. These tests assist in diagnosing:

• Acute hypereosinophilic syndrome (a rare condition resembling leukemia)
• Allergic reactions (to assess the severity of allergies)
• Early-stage Addison's disease
• Parasitic infections
• Vasculitis

Contraindications

There are no known contraindications for eosinophil tests.

Preparation Before the Test

No special preparation is required for a total eosinophil count test. However, certain medications may influence the results, leading to elevated eosinophil levels. These include amphetamines (used as appetite suppressants), some laxatives containing psyllium, certain antibiotics, interferon and tranquilizers.

If you are taking these medications, consult your doctor beforehand. For those undergoing additional tests, fasting for a few hours may be required before the procedure.

Test Procedure

The total eosinophil count test is straightforward. Laboratory personnel will sanitize your arm with sterile alcohol and use a sterile syringe to extract a small blood sample from a vein in your arm. In infants, the blood sample is taken from the heel. The blood is then placed in a blood tube and analyzed with a specialized machine. A portion of the sample is applied to a microscope slide and treated with a specific dye that gives eosinophils their distinct color (ranging from red to orange). The number of eosinophils per 100 visible cells is then counted.

The risks associated with this test are minimal. Some individuals may experience mild pain, dizziness, or bruising when blood is drawn. However, these symptoms typically subside quickly.

Normal and Abnormal Values

• Normal eosinophil percentage: 1–4%.
• Normal eosinophil count: fewer than 500 cells per microliter or between 30 and 350 cells per microliter (depending on the laboratory).

Results and Recommendations (Further Testing)

Low

A reduced eosinophil count is often linked to conditions such as alcohol poisoning or excessive production of steroids within the body (e.g., cortisol).

Normal

A normal eosinophil count suggests a healthy balance of white blood cells. To maintain this, prioritize a nutritious diet, regular physical activity, and routine health evaluations.

High

Elevated eosinophil counts are typically indicative of various medical conditions. Excessively high eosinophil levels, known as eosinophilia, are categorized by severity:

• Mild: 500–1,000 cells per microliter.
• Moderate: 1,500–5,000 cells per microliter.
• Severe: Above 5,000 cells per microliter.

Potential causes of eosinophilia include:

• Adrenal insufficiency
• Allergies, including hay fever
• Asthma
• Autoimmune disorders
• Eczema
• Fungal infections
• Hypereosinophilic syndrome
• Blood-related disorders such as leukemia
• Lymphoma
• Parasitic infections, including worm infestations

Consult the Right Doctor

If your eosinophil count is abnormal, consult a general practitioner for a proper diagnosis and treatment plan. For further evaluation, you may be referred to an internist. For pediatric patients, a pediatrician can provide more specific insights and therapies.

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