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Wheat and Tri a 19, Tri a 20, and Tri a 21 IgE Antibodies [RAST], Qualitative — Deprecated

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

A blood test that checks for IgE antibodies to three wheat proteins—Tri a 19, Tri a 20, and Tri a 21—to help evaluate possible wheat allergy.

Quick summary

["Detectable wheat-specific IgE may indicate immune sensitization, but symptoms and other findings are needed to diagnose allergy."]

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

Key facts at a glance

LOINC
82605-7
Short code
Deprecated Wheat (nTri a) 19+20+21 IgE RAST Ql
Synonyms
Deprecated Wheat (nTri a) 19+20+21 IgE 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 legacy blood test measures IgE antibodies directed against three wheat proteins called Tri a 19, Tri a 20, and Tri a 21. The results are reported qualitatively, such as detected or not detected.

Why might I need this test?

Your clinician may order this test when you have symptoms associated with eating wheat, such as hives, swelling, wheezing, vomiting, or abdominal discomfort. It can help determine whether wheat-specific IgE antibodies are present.

How is the test performed?

A blood sample is collected and analyzed in a laboratory for IgE antibodies that bind to the selected wheat proteins. The result indicates whether antibodies to these components were detected.

How do I prepare for the test?

This test usually requires no fasting or special preparation. Tell your clinician about your symptoms, possible wheat exposures, allergies, and any medicines you are taking, and follow any instructions provided with the order.

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

Wheat component IgE panel

Frequently asked questions

Does a positive result mean I definitely have wheat allergy?
No. It shows that wheat-specific IgE antibodies are present, but the result must be compared with your symptoms and medical history to determine whether you have a clinically relevant allergy.
What are Tri a 19, Tri a 20, and Tri a 21?
They are specific proteins, or components, found in wheat. Testing for individual components provides more detailed information than a general wheat-IgE test alone.
Should I avoid wheat before taking this test?
Do not intentionally avoid wheat unless your clinician tells you to. Your normal dietary exposure and symptoms can help the clinician interpret the test accurately.
  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