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Weed Allergen Mix 20.9-Specific IgE, Serum

Published: August 9, 2026Updated: August 17, 2026

A blood test that measures IgE antibodies to a mixture of common weed allergens to help evaluate possible weed pollen allergy.

Quick summary

["Detectable weed-specific IgE can indicate an immune sensitization to weed pollen, but it must be interpreted alongside your symptoms and exposure history."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
82039-9
Short code
Weed Allerg Mix209 IgE RAST
Synonyms
Weed Allerg Mix209 IgE RAST
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
Method
multidisk
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 measures allergen-specific IgE antibodies in your blood against a mixture of common weed pollens. IgE is an antibody produced by the immune system in response to an allergen.

Why might I need this test?

Your clinician may order this test if you have sneezing, congestion, watery eyes, wheezing, or other symptoms that occur around weeds, grass, or outdoor pollen exposure. It may also help identify which weed allergens are most likely to trigger your symptoms.

How is the test performed?

A blood sample is collected and analyzed in a laboratory for IgE antibodies to the included weed allergens. The report identifies the allergens that produced a measurable immune response.

How do I prepare for the test?

This test usually requires no fasting or special preparation. Tell your clinician about any antihistamines or other allergy medicines you are taking, because they may affect allergy testing; do not stop prescribed medication unless instructed.

Reference range

Adult: 10-40 U/LN/A

Specimen: serum

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

Weed Allergen Mix 20.9-Specific IgE

Frequently asked questions

Does a positive result mean I am allergic to every weed?
No. The result shows sensitization to one or more allergens in the mixture, not necessarily to every weed. Your clinician can help determine which specific weeds are relevant to your symptoms.
Can I have symptoms even if this test is negative?
Yes. A negative result may occur if the responsible allergen is not included in the mixture, if antibody levels are below the laboratory's detection limit, or if your symptoms are caused by another condition. Your clinician will interpret the result in context.
Should I stop taking allergy medicine before this test?
Do not stop medication without advice from your clinician. Antihistamines and some other treatments can affect the interpretation of allergy testing, so discuss all medicines and supplements beforehand.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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