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Test Code CASHR Cashew, IgE with Reflex to Cashew Component, IgE, Serum


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: 0.6 mL

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


Secondary ID

618845

Useful For

Evaluation of patients with suspected cashew allergy

Highlights

The determination of the relative amount of IgE antibody to total cashew, and IgE antibodies to the specific cashew component, may aid in assessment of the potential strength and type of allergenic response to cashew.

 

IgE antibody to total cashew will be initially tested.

 

If detectable total cashew IgE antibody is present, an additional specific component to the cashew allergen antibody testing will be performed. This is comprised of testing for IgE antibodies to the potential allergen Ana o 3.

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
CASHX Cashew Component, IgE, S No No

Testing Algorithm

Testing begins with analysis of cashew-specific total IgE. If the cashew-specific total IgE result is negative (<0.10 kU/L), testing is complete.

 

If the cashew-specific total IgE result is 0.10 kU/L or more, then the cashew component (Ana o 3) test will be performed at an additional charge.

Method Name

Fluorescent Enzyme Immunoassay (FEIA)

Reporting Name

Cashew Component Reflex, S

Specimen Type

Serum

Specimen Minimum Volume

0.4 mL

Specimen Stability Information

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

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Clinical Information

Allergies to tree nuts are relatively prevalent and can result in severe reactions. The main culprits in tree nut allergies include walnut, almond, pistachio, cashew, pecan, hazelnut, macadamia, Brazil nut, and pine nuts. Tree nut allergy often appears in young children and estimates of prevalence range from 0.1% to greater than 5% of the population, dependent on geographical region.

 

In the case of nut-induced allergic reactions, as with many other foods, symptoms usually present within minutes of ingestion. Over 80% of reactions to tree nuts involve allergy related respiratory symptoms. Tree nut allergies are one of the most dangerous types of allergic reaction with 20% to 40% of cases of related anaphylaxis and 70% to 90% of fatalities attributable to nut exposure, including peanut exposure.

 

Ana o 3 is a heat and digestion stable storage protein found in high abundance in cashew nuts. Approximately 80% of those with cashew allergy exhibit reactivity to the Ana o 3 component. Cashew nut allergy is often associated with severe reactions. Sensitization with Ana o 3 is associated with anaphylaxis in system reactions.

 

Severe reactions in those with cashew nut allergy occur at a higher frequency than in those with peanut allergy. Cashews can be found in Asian cuisines, pesto, and nut butter. Cooking will not destroy the allergenic potential of Ana o 3 f. In addition to being severe, cashew nut allergy is persistent and can manifest early in life. Co-sensitization has been repeated between pistachio, walnuts, and, to a lesser extent, hazelnut.

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

Concentrations of 0.70 kU/L or more (class 2 and above) will flag as abnormally high.

Reference values apply to all ages.

Interpretation

When detectable total cashew IgE antibody is present (≥0.10 IgE kUa/L), additional specific component IgE antibody testing will be performed. If a potential specific allergenic cashew component IgE is detectable (≥0.10 IgE kUa/L), an interpretive report will be provided.

 

When the sample is negative for total cashew IgE antibody (<0.10 IgE kUa/L), further testing for specific cashew component IgE antibodies will not be performed. A negative IgE result for total cashew antibody may indicate a lack of sensitization to the potential cashew allergenic component.

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 is then 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)

Day(s) Performed

Monday through Friday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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
CASHR Cashew Component Reflex, S 6718-1

 

Result ID Test Result Name Result LOINC Value
CASH1 Cashew, IgE, S 6718-1

Forms

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