Lab Test

Peanut IgE with Reflex to Components

Peanut (f13), Ara h 1 (f422), Ara h 2 (f423), Ara h 3 (f424), Ara h 8 (f427), Ara h 9 (f352), EPIC: LAB 7146, SOFT: PWRTC

Test Codes

EPIC: LAB 7146, SOFT: PWRTC

Specimen Collection Criteria

Collect: One Gold-top serum separator tube (SST).

  • Volume of serum required per test: 100 mcL
  • One filled 5 mL gold-top serum separator tube is sufficient to perform approximately 20 allergen-specific IgE tests. 

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged collection tube within two hours of collection.

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8°C or 36-46°F)

Rejection Criteria

  • Plasma specimens.
  • Severely lipemic or hemolyzed specimens.

In-Lab Processing

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells.  Room temperature is acceptable for a maximum of two hours.

Storage

Centrifuged SST Tubes and Microtainers® with Separator Gel:
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers® without Separator Gel:
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs):
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 1 month

Specimen Storage in Department Prior to Disposal
Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak, Special Testing Laboratory

Performed

Monday - Friday
Results usually available the next business day

Reference Range

Range (kU/L)

Class

Interpretation

Less than or equal to 0.10

0

Negative

0.10 -0.34

0/1

Equivocal/Borderline

0.35-0.69

1

Low

0.70-3.49

2

Medium

3.50-17.49

3

High

17.50-49.99

4

Very High

50.0-100.0

5

Very High

Greater than 100

6

Very High

Test Methodology

Fluorescence Enzyme Immunoassay (FEIA)

Clinical Utility

A peanut allergy diagnosis is based on a clinical history of symptoms after exposure to peanut (Arachis hypogaea), and is supported by a positive specific serum IgE (sIgE) and/or a positive skin prick test (SPT).  Both these tests provide evidence of allergen-specific sensitization, which does not necessarily equate to the presence of allergic symptoms after exposure to the sensitizing allergen (clinical allergy).  One reason why standard peanut sIgE (i.e. total peanut) and SPT differentiate poorly between asymptomatic sensitization and patients with peanut allergy, is that the antigen source used for these tests is derived from crude natural peanut extracts that contain both allergenic and non-allergenic molecules. Component-based testing assesses specific IgE to individual peanut allergens or components, and has been shown to correlate better to clinical peanut allergy.

 Peanut Components

Ara h 1, Ara h 2, Ara h 3

  • Seed storage protein components; All are considered major peanut allergens.
  • Sensitization may indicate an increased risk of a systemic allergy response upon exposure to peanut.

 Ara h 8, Ara h 9

  • Ara h 8 is member of the PR-10 protein family and a Bet v 1-homologue, which is a major birch allergen component.  Ara h 9 is a lipid transfer protein also found in pitted fruits.
  • Sensitization to Ara h 8 and/or Ara h 9 are associated with milder peanut allergies.  A positive test may due to cross-reactivity in patients sensitized to birch pollen or pitted fruits, respectively.

CPT Codes

86003 (f13)
86008 (f422)
86008 (f423)
86008 (f424)
86008 (f427)
86008 (f352)

Contacts

Last Updated

10/23/2019

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This directory currently reflects information only for specimens collected and/or processed at the
Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.