Eosinophil count (serum or plasma)
This test measures the number of eosinophils, a type of white blood cell, in your blood. Eosinophils help fight infections caused by parasites, allergens, and certain types of cancer.
["Eosinophils help your body defend against harmful substances and infections."]
Key facts at a glance
- LOINC
- 9420-1
- Short code
- E histolyt Ab Titr Ser CF
- Synonyms
- E histolyt Ab Titr Ser CF
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- comp-fix
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why Might This Test Be Done?
Your doctor may order this test to investigate symptoms like persistent itching, skin rashes, asthma, or unexplained allergies. It can also help diagnose conditions such as parasitic infections, certain cancers (like leukemia), or autoimmune diseases.
What to Expect Before the Test
No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, which usually takes a few minutes. If you’re on blood thinners, let your doctor know before the test.
What the Results Mean
Eosinophil counts can vary widely. High levels may suggest allergic reactions, infections, or certain diseases. Low levels might indicate immune suppression or other health conditions. Your doctor will interpret the results in the context of your overall health and symptoms.
Common Conditions Linked to Eosinophil Levels
Elevated eosinophil counts are often seen in allergic disorders, parasitic infections, asthma, eosinophilic esophagitis, and some types of cancer. Low levels may be associated with conditions affecting immune function or chronic illnesses.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: Eosinophils play a key role in immune responses, particularly against parasites and allergens. Abnormal counts can signal underlying health issues that require further evaluation by your healthcare provider.
Short name
Eosinophil Level
Frequently asked questions
What causes eosinophil levels to rise?
What does a normal range of eosinophils mean?
Can diet or lifestyle affect eosinophil counts?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy