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Eosinophil count in serum/plasma (absolute)

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 fight infections and respond to allergies and inflammation.

Quick summary

["Eosinophils can signal allergic reactions, infections, or other immune responses."]

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

Key facts at a glance

LOINC
22286-9
Short code
E histolyt Ab Titr Ser
Synonyms
E histolyt 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 Might You Need This Test?

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, or autoimmune disorders.

What to Expect Before the Test

No special preparation is needed for this test. You’ll have a small needle inserted into your vein (usually in your arm) to draw blood. The process takes about 5 minutes, and you may feel a brief pinch or discomfort.

What the Results Mean

Elevated eosinophil counts may indicate allergic reactions, infections, or inflammatory conditions. Lower-than-normal levels might suggest certain blood disorders or immune deficiencies. Your doctor will interpret results in the context of your symptoms and medical history.

Common Conditions Linked to Eosinophil Levels

High eosinophil counts can be linked to allergies, asthma, parasitic infections, certain cancers (like lymphoma), or autoimmune diseases. Low levels may be associated with conditions like aplastic anemia or other blood disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Eosinophil CBC

Frequently asked questions

What causes false high or low eosinophil results?
False elevations can occur due to recent infections, certain medications (like steroids), or lab errors. False low levels may result from recent blood transfusions, certain medications, or lab processing issues. Always discuss your results with your healthcare provider.
How long does it take to get results from this test?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your doctor will contact you once they have the results.
Can I eat or drink before this blood test?
You can eat and drink normally before this test, as no special preparation is required. However, inform your doctor about any medications you’re taking, as some may affect your blood count.
  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