What is eosinophils in blood test

Overview

Eosinophils are specialized white blood cells that play a crucial role in immune response, particularly in combating parasitic infections and allergic reactions. When doctors request a complete blood count (CBC) test, they measure eosinophil levels to assess immune function and detect underlying health conditions.

Normal Eosinophil Ranges

In a healthy adult, eosinophils typically comprise 1-4% of total white blood cells. When expressed as an absolute count, normal levels range from 0 to 500 cells per microliter of blood. However, these reference ranges can vary slightly between laboratories depending on their testing methods and population data.

What Elevated Eosinophils Indicate

Elevated eosinophil counts (eosinophilia) may suggest several conditions:

• Allergic reactions including allergic asthma and seasonal allergies
• Parasitic infections such as hookworms, roundworms, or tapeworms
• Fungal infections and certain bacterial infections
• Autoimmune disorders like celiac disease and lupus
• Leukemia and lymphomas in certain cases
• Medications including some antibiotics and anti-inflammatory drugs

Low Eosinophil Counts

While less common, low eosinophil counts (eosinopenia) may result from steroid use, acute bacterial infections, or bone marrow disorders. Doctors investigate both elevated and depressed eosinophil levels in context with other test results and clinical symptoms.

Testing and Interpretation

Eosinophil counts are obtained through standard blood tests, particularly the complete blood count (CBC) with differential. Additional testing such as allergy tests, parasitic screenings, or imaging may be necessary depending on eosinophil levels and clinical presentation. Healthcare providers interpret results in conjunction with symptoms, medical history, and other laboratory values.