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Wheat Bran IgG4 Radioallergosorbent Test (RAST), Qualitative — Deprecated

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

A historical blood test for IgG4 antibodies directed against wheat bran, used in evaluating suspected food-related reactions.

Quick summary

["This deprecated test detects wheat-bran-specific IgG4 antibodies, but a positive result alone does not confirm food allergy."]

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

Key facts at a glance

LOINC
26412-7
Short code
Deprecated Wheat Bran IgG4 RAST Ql
Synonyms
Deprecated Wheat Bran IgG4 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?

The wheat bran IgG4 RAST is a blood test that looked for IgG4 antibodies against wheat bran. RAST is an older laboratory method for measuring antibodies that bind to a specific allergen. This test has been deprecated and may no longer be available.

Why might I need this test?

It was historically considered when a person had gastrointestinal or other symptoms thought to be related to wheat or wheat bran. Results were intended to be interpreted alongside the medical history, diet, and other allergy testing.

How is the test performed?

Blood is collected and the serum is exposed to a wheat-bran allergen reagent in a RAST-style laboratory assay. Any wheat-bran-specific IgG4 antibodies that bind can then be detected, with the result reported as positive or negative.

How do I prepare for the test?

No special preparation is usually required, and fasting is generally unnecessary. Because the test is deprecated, contact the ordering clinician or laboratory to confirm whether an alternative test is available and whether any preparation instructions apply.

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

Wheat Bran IgG4 RAST

Frequently asked questions

Does a positive result mean I am allergic to wheat?
No. Detectable wheat-bran-specific IgG4 antibodies can occur without clinical allergy and do not confirm an immediate IgE-mediated reaction. Your clinician should interpret the result in context.
Is this test still available?
The test is deprecated, so many laboratories no longer perform it. The ordering clinician can recommend a currently available alternative if further evaluation is needed.
Can this test diagnose celiac disease?
No. Celiac disease is evaluated with specific antibody tests and, when appropriate, a biopsy of the small intestine. This older wheat-bran IgG4 test is not a celiac diagnostic test.
  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