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Eosinophil count in serum/plasma (qualitative or semi-quantitative)

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

This test checks the presence and relative amount of eosinophils, a type of white blood cell, in your blood. Eosinophils help fight certain infections and respond to allergies or inflammatory conditions.

Quick summary

["Eosinophils may rise in response to allergies, infections, or other immune reactions."]

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

Key facts at a glance

LOINC
111463-6
Short code
E histolyt Ab Msmt Ser
Synonyms
E histolyt Ab Msmt 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

When Might You Need This Test?

Your doctor may order this test if you have symptoms like persistent itching, skin rashes, asthma, or unexplained allergies. It could also be used to monitor conditions like parasitic infections, certain cancers, or autoimmune disorders.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood. If you’re on blood-thinning medication, let your doctor know before the test.

What the Results Mean

Results are qualitative (present or not present) or semi-quantitative (approximate levels). High eosinophil counts may indicate allergies, infections, or other immune-related issues. Low or normal levels suggest typical immune function.

Common Conditions Linked to Eosinophil Levels

Elevated eosinophils are often seen in allergic reactions, asthma, parasitic infections, certain cancers (like lymphoma), or inflammatory diseases. Low levels may occur with stress, infections, or certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Eosinophil test (qualitative)

Frequently asked questions

Why might my doctor ask for this test?
Your doctor may use this test to diagnose or monitor conditions affecting your immune system, allergies, or chronic illnesses. It helps track how your body is responding to treatments or infections.
What does a high eosinophil count usually mean?
A high eosinophil count often signals an allergic reaction, parasitic infection, or an inflammatory process. It can also be seen in certain cancers or autoimmune disorders, so further testing may be needed to determine the cause.
Can I eat or drink before this test?
You can eat and drink normally before this test, unless your doctor has specific instructions. Avoiding alcohol or caffeine may help reduce stress, but it’s best to follow your doctor’s advice.
  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