Alternaria alternata-Specific IgG4 Antibody, RAST, Qualitative (Deprecated)
A qualitative RAST test that detects IgG4 antibodies to Alternaria alternata, a mold. This legacy test is listed as deprecated and is not routinely used to diagnose mold allergy.
["Detectable Alternaria alternata-specific IgG4 usually suggests prior exposure but does not by itself confirm an active mold allergy."]
Key facts at a glance
- LOINC
- 26404-4
- Short code
- Deprecated A alternata IgG4 RAST Ql
- Synonyms
- Deprecated A alternata IgG4 RAST Ql
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 7
- Ref high
- 56
- Critical range
- — – 500 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84484
- SNOMED
- 302773008
- 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 designed to detect IgG4 antibodies directed against Alternaria alternata, a mold commonly found in the environment. RAST stands for radioallergosorbent test, a type of allergen-antibody assay. The test is listed as deprecated.
Why might I need this test?
It may have been ordered to assess immune exposure to Alternaria alternata in a person with possible mold-related respiratory or skin symptoms. It should be interpreted with the medical history and other allergy testing because IgG4 antibodies do not necessarily indicate a clinically significant allergy.
How is the test performed?
If the legacy test is still available, a blood sample is analyzed using a RAST-type assay to determine whether Alternaria alternata-specific IgG4 is detectable. The result is qualitative, meaning it is reported as detected or not detected rather than with a numeric concentration.
How do I prepare for the test?
No special preparation is usually required unless the laboratory provides different instructions. Tell your clinician about allergies, recent immunotherapy, immune-system conditions, and medicines that may affect the immune response.
Reference range
Adult males: 7-56 U/L; Adult females: 7-43 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.
Detectable Alternaria alternata-specific IgG4 generally indicates that the immune system has encountered this mold, but it does not prove that mold exposure is causing current symptoms. A result that is not detected does not completely rule out prior exposure. Because this test is deprecated, newer, standardized methods and the overall clinical picture should guide interpretation.
Short name
Alternaria alternata IgG4 (RAST)
Frequently asked questions
Does a positive result mean I have an Alternaria alternata allergy?
What is the difference between IgG4 and IgE testing?
Why is this test marked 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