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Peanut-Specific IgE, Radioallergosorbent Test (RAST), Qualitative

Published: August 9, 2026Updated: August 17, 2026

A blood test that detects IgE antibodies directed against peanut proteins to assess possible peanut sensitization.

Quick summary

["A positive result indicates sensitization to peanut, but it does not by itself confirm a clinical peanut allergy."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
81992-0
Short code
Deprecated Peanut (rAra h) 3 IgE RAST Ql
Synonyms
Deprecated Peanut (rAra h) 3 IgE RAST Ql
Category
liver
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84484
SNOMED
302774002
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

What is this test?

This qualitative blood test measures IgE antibodies that react with peanut proteins. It is sometimes called a peanut RAST or peanut-specific IgE test.

Why might I need this test?

A clinician may order this test when there is concern about a peanut allergy, particularly after an unexplained skin reaction, hives, swelling, wheezing, or other symptoms after eating peanut.

How is the test performed?

A blood sample is collected and tested in the laboratory for peanut-specific IgE using an immunoassay-based method. The result is reported as positive or negative, although some laboratories also provide a measurement level.

How do I prepare for the test?

Fasting is generally not required. Antihistamines and certain other medicines can affect allergy-test results, so tell your clinician about all medicines and supplements before testing; do not stop prescribed medicines unless instructed.

Reference range

Adult: 10-40 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Peanut-Specific IgE

Frequently asked questions

Does a positive peanut IgE test mean I am allergic to peanut?
Not necessarily. It indicates sensitization, and your clinician will interpret it alongside symptoms, exposure history, and sometimes other allergy tests.
Is this the same as a skin-prick test?
No. This test uses a blood sample to detect peanut-specific IgE, while a skin-prick test evaluates an immediate skin reaction after peanut is placed on the skin.
Can I stop my allergy medicine before the test?
Only if your clinician instructs you to. Antihistamines may reduce test results, and stopping a prescribed medicine without guidance could be unsafe.
  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 17, 2026. · Read our editorial policy