Eosinophil count in serum/plasma (qualitative or semiquantitative)
This test checks the presence or level of eosinophils, a type of white blood cell, in your blood. Eosinophils help fight infections and respond to allergies or inflammatory conditions.
["Eosinophils can signal allergic reactions, infections, or other immune responses—your doctor may order this test for symptoms like itching, rashes, or unexplained fatigue."]
Key facts at a glance
- LOINC
- 22289-3
- Short code
- E histolyt IgM Ser-aCnc
- Synonyms
- E histolyt IgM Ser-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82784
- 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 This Test Is Done
Doctors may order this test to diagnose or monitor conditions like allergies, asthma, parasitic infections, certain cancers (e.g., leukemia), or autoimmune diseases. It can also help evaluate symptoms like persistent itching, skin rashes, or digestive issues that don’t improve with other treatments.
What to Expect Before the Test
No special preparation is needed. You’ll likely have a simple blood draw, usually at a doctor’s office or lab. If you’re on blood thinners, let your provider know before the test.
What the Results Mean
Results are qualitative (present/absent) or semiquantitative (approximate levels). High eosinophil counts may indicate allergies, infections, or inflammatory diseases, while very low counts could signal immune suppression or other health concerns. Your doctor will interpret results in the context of your symptoms and medical history.
Common Conditions Linked to Eosinophil Levels
Elevated eosinophils are often seen in allergic reactions, parasitic infections, asthma, or certain cancers. Low levels may suggest conditions like HIV, certain autoimmune diseases, or prolonged stress on the immune system.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Eosinophils play a key role in defending against parasites and regulating immune responses. They release chemicals that can cause inflammation or allergic symptoms. High levels may indicate an overactive immune response, while low levels could signal weakened immune function or hidden infections. Your doctor will use these results alongside other tests to guide treatment.
Short name
Eosinophil Screen/Confirm
Frequently asked questions
How long does it take to get my results?
Can I eat or drink before this test?
Is there any risk or discomfort with this test?
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