Walnut Tree, IgE, Serum - Seattle Children's Hospital

Reporting Name

Walnut Tree, IgE

Seattle Children's Hospital Note:

Clinical System Name: Allergen Walnut Tree IgE

Useful For

Establishing a diagnosis of an allergy to walnut tree

Defining the allergen responsible for eliciting signs and symptoms

Identifying allergens:

-Responsible for allergic response and/or anaphylactic episode

-To confirm sensitization prior to beginning immunotherapy

-To investigate the specificity of allergic reactions to insect venom allergens, drugs, or chemical allergens

Ordering Guidance

For a listing of allergens available for testing, see Allergens - Immunoglobulin E (IgE) Antibodies.

Specimen Required

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL for every 5 allergens requested

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.

Specimen Type

Serum

Specimen Minimum Volume

For 1 allergen: 0.3 mL
For more than 1 allergen: (0.05 mL x number of allergens) + 0.25 mL deadspace

Specimen Stability Information

Specimen Type	Temperature	Time	Special Container
Serum	Refrigerated (preferred)	14 days
	Frozen	90 days

Day(s) Performed

Monday through Friday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Method Name

Fluorescence Enzyme Immunoassay (FEIA)

Method Description

Specific IgE from the patient's serum reacts with the allergen of interest, which is covalently coupled to an ImmunoCAP. After washing away nonspecific IgE, enzyme-labeled anti-IgE antibody is added to form a complex. After incubation, unbound anti-IgE is washed away, and the bound complex incubated with a developing agent. After stopping the reaction, the fluorescence of the eluate is measured. Fluorescence is proportional to the amount of specific IgE present in the patient's sample (ie, the higher the fluorescence value, the more IgE antibody is present).(Package insert: ImmunoCAP System Specific IgE FEIA. Phadia; Rev 06/2020)

Reference Values

Class	IgE kU/L	Interpretation
0	<0.10	Negative
0/1	0.10-0.34	Borderline/equivocal
1	0.35-0.69	Equivocal
2	0.70-3.49	Positive
3	3.50-17.4	Positive
4	17.5-49.9	Strongly positive
5	50.0-99.9	Strongly positive
6	≥100	Strongly positive

Reference values apply to all ages.

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

86003

LOINC Code Information

Test ID	Test Order Name	Order LOINC Value
WALN	Walnut Tree, IgE	6274-5

Result ID	Test Result Name	Result LOINC Value
WALN	Walnut Tree, IgE	6274-5

Special Instructions

Allergens - Immunoglobulin E (IgE) Antibodies

Report Available

Same day/1 to 3 days

Reject Due To

Gross hemolysis	OK
Gross lipemia	OK

Forms

If not ordering electronically, complete, print, and send an Allergen Test Request (T236) with the specimen.

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Test Code AlWalnutTr Walnut Tree, IgE, Serum