Allergen-Specific IgE Antibody (RAST), Qualitative
A qualitative blood test for allergen-specific IgE that helps identify sensitization to selected triggers such as pollen, foods, dust mites, or animal dander.
["This test looks for IgE antibodies to specific allergens, but results must be interpreted alongside your symptoms and medical history."]
Key facts at a glance
- LOINC
- 33312-0
- Short code
- Deprecated R nigricans IgG RAST Ql
- Synonyms
- Deprecated R nigricans 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 blood test, commonly called RAST, that detects allergen-specific IgE antibodies. It may be ordered for one allergen or as a panel. The RAST format may be listed as deprecated in some laboratory catalogs, and a current allergen-specific IgE assay may be used instead.
Why might I need this test?
Your clinician may order this test to evaluate possible allergies to foods, pollen, dust mites, animal dander, insect venom, or other triggers. It can help identify which allergens deserve further evaluation or avoidance counseling.
How is the test performed?
A blood sample is collected from a vein and tested in the laboratory for IgE directed against selected allergens. Some laboratories use a panel, while others test only the allergens requested by your clinician.
How do I prepare for the test?
Fasting is usually not required. Antihistamines and some other allergy medicines may affect results, so tell your clinician about all medications and supplements before testing. Do not stop prescribed medicines unless your clinician instructs you to do so.
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.
◆Associated findings1
Short name
Allergen-Specific IgE (RAST)
Frequently asked questions
What does a positive RAST result mean?
Does a positive result confirm an allergy?
Should I stop taking allergy medicine before the test?
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