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Rye-Specific IgG Antibody — Radioallergosorbent Test (RAST), Qualitative (Deprecated)

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

A deprecated, qualitative rye-specific immunoglobulin test using the RAST method. Because RAST is usually an IgE method, confirm the report’s antibody class and availability.

Quick summary

["This historical test may detect rye-specific antibodies, but the exact antibody class should be confirmed because RAST ordinarily measures IgE rather than IgG."]

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

Key facts at a glance

LOINC
21505-3
Short code
Deprecated Rye IgG RAST Ql
Synonyms
Deprecated Rye 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 laboratory test intended to detect antibodies associated with rye exposure or sensitivity. The order name is marked as deprecated, and it combines “IgG” with RAST, although RAST is generally used to measure allergen-specific IgE.

Why might I need this test?

It may have been used to evaluate a possible food-related reaction to rye or to assess immune response to rye. The result is most useful when reviewed with your symptoms, exposure history, and other allergy testing.

How is the test performed?

The laboratory tests the submitted specimen for rye-specific antibodies using a RAST-style assay and reports a qualitative result, such as detectable or not detectable. This test is no longer routinely available in many laboratories.

How do I prepare for the test?

No special preparation is usually associated with this type of test. Follow any instructions provided by the ordering clinician or laboratory, and tell the clinician about food reactions, allergy symptoms, and relevant medications.

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

Rye IgG RAST, Qualitative

Frequently asked questions

Does a positive result mean I have a rye allergy?
Not necessarily. A positive antibody result can indicate sensitization or immune response, and it must be interpreted together with symptoms and, when appropriate, confirmatory allergy testing.
Why does the order mention both IgG and RAST?
The order name appears inconsistent because RAST is normally associated with allergen-specific IgE, not IgG. Ask the laboratory or ordering clinician to verify the exact test and result.
Can this test be used to monitor my condition?
It is generally not used for routine monitoring because it is deprecated and its reporting is inconsistent. Current allergy evaluation usually relies on the clinical history and appropriate IgE-based testing.
  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