Oyster-Specific IgG Antibody, Qualitative (RAST) — Deprecated
A qualitative blood test that detects antibodies directed against oyster proteins. This deprecated test is not considered a reliable stand-alone test for oyster allergy.
["A positive result shows an immune response to oyster proteins but does not by itself confirm an oyster allergy."]
Key facts at a glance
- LOINC
- 21438-7
- Short code
- Deprecated Oyster IgG RAST Ql
- Synonyms
- Deprecated Oyster 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 oyster-specific IgG antibodies in a blood sample using a qualitative RAST-type laboratory assay. The result is generally reported as positive or negative.
Why might I need this test?
It may have been ordered to evaluate an immune response after eating oysters or when investigating a suspected food reaction. The test is now deprecated and should not be used alone to diagnose or rule out food allergy.
How is the test performed?
A blood sample is analyzed in the laboratory for antibodies that bind to oyster proteins. The laboratory reports whether oyster-specific IgG was detected.
How do I prepare for the test?
No special preparation is usually specified for this qualitative antibody test. Follow any instructions from your clinician or laboratory, and tell them if you have recently eaten oysters or had a reaction.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A positive result may indicate prior exposure or an immune response to oyster proteins, but it does not necessarily mean you have a clinical oyster allergy. A negative result does not exclude allergy or a reaction. Because this test is deprecated, results should be interpreted alongside symptoms, medical history, and any more appropriate allergy testing.
Short name
Oyster-specific IgG
Frequently asked questions
Does a positive result mean I am allergic to oysters?
Can a negative result rule out oyster allergy?
Why is this test listed as deprecated?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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