Clam-Specific IgG Antibody, Qualitative — RAST
A qualitative blood test for IgG antibodies to clam proteins using a RAST-type method. It is a historical, deprecated allergy test.
["This test detects antibodies to clam, but a positive result does not by itself confirm a clam allergy."]
Key facts at a glance
- LOINC
- 21204-3
- Short code
- Deprecated Clam IgG RAST Ql
- Synonyms
- Deprecated Clam 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 looks for IgG antibodies directed against clam proteins. The RAST designation refers to an older radioallergosorbent testing method, and this test is marked as deprecated and may not be available.
Why might I need this test?
It was historically used to evaluate a possible clam allergy. Food-specific IgG results do not reliably diagnose immediate, IgE-mediated food allergy, so current evaluation usually depends on the exposure history, targeted IgE blood testing, and sometimes skin-prick testing.
How is the test performed?
A blood sample is collected, and the separated serum is exposed to clam allergen in the laboratory. The assay then reports whether clam-specific IgG was detected. Many laboratories now use newer allergy-testing methods instead of RAST.
How do I prepare for the test?
No special preparation or fasting is generally required for this type of blood test. Follow any instructions provided by the laboratory, and consult the ordering clinician before changing food avoidance or allergy medication use.
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 indicates that IgG antibodies to clam were detected, which may reflect previous exposure or a general immune response. It does not by itself mean that a person has a clinically important clam allergy. A negative result also does not completely exclude allergy, and the result should be interpreted with the person's symptoms and exposure history.
Short name
Clam-specific IgG antibody (RAST)
Frequently asked questions
Does a positive result mean I am allergic to clams?
Can this test rule out a clam allergy?
Should I avoid clams if this test is positive?
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