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Barley-Specific IgG, Radioallergosorbent (RAST), Qualitative (Deprecated)

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

A qualitative, deprecated test for barley-specific IgG antibodies, historically used to assess immune exposure to barley.

Quick summary

["A positive result shows barley-specific IgG but does not by itself confirm a barley allergy."]

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

Key facts at a glance

LOINC
21092-2
Short code
Deprecated Barley IgG RAST Ql
Synonyms
Deprecated Barley IgG 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 is a qualitative blood test that detects antibodies directed against barley. It uses the older radioallergosorbent (RAST) method and is marked as deprecated.

Why might I need this test?

It may have been used to evaluate barley exposure or a suspected food-related immune reaction. Because this test is deprecated, clinicians generally rely on the medical history and currently recommended allergy testing.

How is the test performed?

A blood sample is analyzed to determine whether barley-specific IgG antibodies are present. The result is reported as positive or negative rather than as a measured concentration.

How do I prepare for the test?

No special preparation is usually required, and fasting is generally unnecessary. If the test has been ordered, follow any specific instructions provided by the laboratory or healthcare professional.

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

Barley IgG RAST

Frequently asked questions

Does a positive barley IgG RAST result mean I am allergic to barley?
No. It shows the presence of barley-specific IgG antibodies, but food-specific IgG results do not reliably diagnose allergy or predict symptoms.
Why is this test called deprecated?
It is an older test that is no longer routinely recommended or may no longer be available. Current food-allergy evaluation generally uses other clinically validated methods.
Do I need to fast before this test?
Fasting is usually not required. Follow the ordering clinician or laboratory's instructions if they specify otherwise.
  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