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Grass Allergen Mix 2-Specific IgE, Serum — Radioallergosorbent Test (RAST)

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

A blood test that measures IgE antibodies to a mixture of grass allergens, helping evaluate possible grass-pollen allergy.

Quick summary

["A positive result indicates sensitization to one or more tested grass allergens but does not by itself confirm clinical allergy."]

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

Key facts at a glance

LOINC
24486-3
Short code
Grass Allerg Mix2 IgE RAST
Synonyms
Grass Allerg Mix2 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 blood against a mixture of grass allergens. IgE is an immune-system antibody that can develop in response to a particular allergen.

Why might I need this test?

It may be ordered when symptoms such as sneezing, nasal congestion, or itchy eyes occur during grass-pollen seasons. Results can help identify whether grass pollen is a possible trigger, especially when the diagnosis is unclear.

How is the test performed?

A blood sample is collected and tested for IgE directed against the allergens included in the grass mixture. RAST is an older name for this type of testing; many laboratories use automated immunoassays with the same clinical purpose.

How do I prepare for the test?

Fasting is usually not required. Do not stop medications or allergen immunotherapy without instructions from your healthcare professional, and tell the laboratory about any recent biologic treatments that might affect interpretation.

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

Grass Allergy Specific IgE (RAST)

Frequently asked questions

What does a positive grass allergy IgE result mean?
It means your immune system has developed IgE antibodies to one or more tested grass allergens. This is consistent with sensitization and may help explain allergy symptoms, but it must be interpreted alongside your symptoms and exposure history.
Does this test confirm that I have a grass-pollen allergy?
Not by itself. Some people have positive IgE results without symptoms, so your clinician will consider the result along with when and how your symptoms occur.
Do I need to stop allergy medicines before this test?
Usually not, and you should not stop prescribed medicines unless your clinician instructs you to. Tell the laboratory about any allergy immunotherapy or biologic medications you are receiving.
  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