Skip to content

Deprecated Grape IgG Radioallergosorbent Test (RAST), Qualitative

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

A qualitative blood test for antibodies against grape proteins. This older RAST-based test is deprecated and is not routinely used to diagnose food allergy.

Quick summary

["A positive result shows grape-reactive antibodies but does not by itself confirm a symptomatic grape allergy."]

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

Key facts at a glance

LOINC
21314-0
Short code
Deprecated Grape IgG RAST Ql
Synonyms
Deprecated Grape 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 test looks for IgG antibodies directed against proteins found in grapes. It is an older radioallergosorbent test, or RAST, and is now considered deprecated.

Why might I need this test?

It may have been used to assess immune reactivity to grapes or to help investigate a suspected food-related reaction. A newer allergy test or clinical evaluation may be needed because this test is no longer routinely performed.

How is the test performed?

A blood sample is analyzed in the laboratory for grape-specific IgG antibodies. The qualitative result is generally reported as positive or negative, although laboratory terminology may vary.

How do I prepare for the test?

Fasting is usually not required for this type of blood test. Follow the laboratory's instructions, and tell your clinician about any food allergies, symptoms, or medicines such as antihistamines before testing.

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

Grape IgG RAST (deprecated)

Frequently asked questions

Does a positive result mean I am allergic to grapes?
Not necessarily. Food-specific IgG can occur in people without symptoms, so results must be interpreted with your symptoms, medical history, and other allergy testing.
Why is this test called deprecated?
Deprecated means it is an older test that is no longer routinely recommended or performed by many laboratories. Your clinician may use a more current testing method instead.
Can this test explain a reaction after eating grapes?
It cannot confirm the cause of a reaction by itself. A clinician may also consider symptoms, other allergy tests, and—depending on the situation—evaluation for nonallergic causes.
  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