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Eosinophil absolute count (serum/plasma concentration)

Published: August 9, 2026Updated: August 16, 2026

This test measures the number of eosinophils, a type of white blood cell, in your blood. Eosinophils help your body fight infections and respond to allergies.

Quick summary

["Eosinophil counts help diagnose and monitor conditions like allergies, asthma, or certain infections."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
43038-9
Short code
EV Ab Titr Ser
Synonyms
EV Ab Titr Ser
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Might Be Ordered

Your doctor may order this test if you have symptoms like persistent itching, skin rashes, or unexplained allergies. It could also be used to check for conditions like parasitic infections, inflammatory diseases, or reactions to medications.

What to Expect Before the Test

No special preparation is needed. A blood sample is taken from a vein, usually in your arm. You may feel a slight pinch, but it’s quick and painless.

What the Results Mean

Elevated eosinophil counts may indicate allergies, asthma, or certain infections. Lower-than-normal levels might suggest immune system issues or other health concerns. Your doctor will interpret results in the context of your symptoms and medical history.

Common Conditions Monitored

This test is often used to diagnose or track conditions like allergic reactions, parasitic infections, eosinophilic esophagitis, or certain autoimmune diseases.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Elevated eosinophils can signal chronic inflammation, allergic responses, or parasitic infections. Doctors use these results alongside other tests and symptoms to guide treatment.

Short name

Eosinophil Count

Frequently asked questions

What causes eosinophils to be high?
High eosinophil counts can result from allergies, asthma, parasitic infections, certain cancers, or inflammatory conditions. Stress or medications may also temporarily affect levels.
How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time.
Can I eat or drink before this test?
You can eat and drink normally before this test, as no special preparation is required.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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