Deprecated Cottonwood-Specific IgE, Qualitative (RAST)
A qualitative blood test for cottonwood-specific IgE antibodies, used to assess allergic sensitization. A positive result alone does not confirm that cottonwood causes your symptoms.
["A positive result suggests an immune reaction to cottonwood, but your symptoms and exposure history must also be considered."]
Key facts at a glance
- LOINC
- 58021-7
- Short code
- Deprecated Cottonwood IgG RAST Ql
- Synonyms
- Deprecated Cottonwood 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 qualitative test checks a blood sample for IgE antibodies directed against cottonwood, a tree whose pollen can cause seasonal allergies. RAST is an older type of allergy testing method, and this test entry is marked as deprecated.
Why might I need this test?
Your clinician may order it to evaluate possible cottonwood allergy, especially if you have sneezing, watery eyes, nasal congestion, wheezing, or other symptoms when exposed to cottonwood pollen.
How is the test performed?
A blood-based sample is analyzed for cottonwood-specific IgE using a RAST-type laboratory method. The result is reported as positive or negative rather than as a measured concentration.
How do I prepare for the test?
No special preparation is usually required. Tell your clinician about any antihistamines or other allergy medicines you are taking because they may affect the result; do not stop a prescribed medicine unless instructed.
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 the immune system has developed IgE antibodies to cottonwood, which is consistent with sensitization. It does not by itself prove that cottonwood is the cause of your symptoms or predict the severity of an allergic reaction. Your clinician should interpret the result alongside your history, examination, and other allergy tests.
Short name
Cottonwood IgE test
Frequently asked questions
Does a positive result mean I am allergic to cottonwood?
Can this test tell me which symptoms are caused by cottonwood?
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