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Red Snapper IgG Radioallergosorbent Test (RAST), Qualitative — Deprecated

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

A qualitative blood test for IgG antibodies to red snapper. This deprecated food-antibody test is not a reliable way to diagnose seafood allergy.

Quick summary

["A positive result shows an immune response to red snapper but does not by itself confirm an allergy."]

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

Key facts at a glance

LOINC
21524-4
Short code
Deprecated Red Snapper IgG RAST Ql
Synonyms
Deprecated Red Snapper 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 red snapper-specific IgG antibodies in a blood sample using a radioallergosorbent test method, or RAST. It is a qualitative test, meaning it reports detectable or undetectable antibodies rather than a measured concentration.

Why might I need this test?

It may have been ordered to evaluate a suspected reaction to red snapper or other fish. However, food-specific IgG testing is generally not recommended for diagnosing allergy because IgG can reflect exposure without causing symptoms.

How is the test performed?

A blood sample is analyzed in the laboratory for antibodies that bind to red snapper antigens. Because this test is deprecated, the laboratory may no longer perform it and may suggest an alternative.

How do I prepare for the test?

No special preparation is usually required for a routine blood draw. Follow any instructions provided by the laboratory, and tell the healthcare professional if you have recently eaten fish or have had a reaction to seafood.

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

Red snapper IgG RAST, qualitative

Frequently asked questions

Does a positive result mean I am allergic to red snapper?
No. Red snapper-specific IgG can occur in people who tolerate the food, so this result alone does not establish a true allergy.
What symptoms can suggest a red snapper allergy?
Possible symptoms include hives, swelling, wheezing, vomiting, abdominal pain, or dizziness, particularly soon after eating fish. Severe symptoms require urgent medical attention.
Why is this test described as deprecated?
It is an older food-specific IgG test with limited usefulness for diagnosing allergy. The ordering clinician can discuss more appropriate testing if clinically indicated.
  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