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Test Catalog

Test ID: PEAN    
Peanut, IgE, Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

Establishing a diagnosis of an allergy to peanut

 

Defining the allergen responsible for eliciting signs and symptoms

 

Identifying allergens:

-Responsible for allergic disease 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

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Peanut allergy is one of the most common food allergies in the United States, with an estimated prevalence of approximately 1% to 2%.(1) The clinical symptoms of peanut allergy may range from relatively mild, such as rhinorrhea, pruritus, or nausea, to a systemic and potentially life-threatening anaphylactic reaction. The diagnosis of peanut allergy is based upon the presence of compatible clinical symptoms in the context of peanut exposure, with support from identification of potential peanut-specific IgE allergen antibodies, either by skin testing or in vitro serology testing.

 

In vitro serology testing has generally focused on assessing for the presence of total peanut IgE antibodies. These antibodies are identified by immunoassay in which the capture allergen is an extract prepared from natural peanut raw material. Most studies have demonstrated a correlation between the amount of total peanut IgE allergen antibody present and an increased likelihood of a clinical allergic response.

 

Clinical manifestations of immediate hypersensitivity (allergic) diseases are caused by the release of proinflammatory mediators (histamine, leukotrienes, and prostaglandins) from IgE-sensitized effector cells (mast cells and basophils) when cell-bound IgE antibodies interact with allergen.

 

Once an elevated antibody response to total peanut IgE extract is established, assessment for the presence of specific IgE antibodies to the most common individual peanut allergenic components may be considered.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

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

> or =100

Strongly positive

Concentrations > or =0.70 kU/L (Class 2 and above) will flag as abnormally high.

Interpretation Provides information to assist in interpretation of the test results

Detection of IgE antibodies in serum (Class 1 or greater) indicates an increased likelihood of allergic disease as opposed to other etiologies and defines the allergens that may be responsible for eliciting signs and symptoms.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Results from peanut specific IgE antibody testing must be interpreted in the context of patient’s clinical evaluation and history of allergen exposures.

 

Negative results for IgE to total peanut and any peanut components do not completely exclude the possibility of clinically relevant allergic responses upon exposure to peanut. Clinical correlation of results from in vitro IgE testing with patient history of allergic or anaphylactic responses to peanut is recommended.

 

Positive results for IgE to total peanut or any peanut components are not diagnostic for peanut allergy, and only indicate patient may be sensitized to peanut or a cross-reactive allergen. Recommend correlation of results from in vitro IgE testing with patient history of allergic or anaphylactic responses to peanut.

 

Testing for IgE antibodies may not be useful in patients previously treated with immunotherapy to determine if residual clinical sensitivity exists, or in patients in whom the medical management does not depend upon identification of allergen specificity.

 

Some patients with significantly elevated concentrations of total peanut IgE antibodies do not have any reaction when administered a peanut oral food challenge. This may be due to the presence of an IgE antibody specific for a nonallergenic protein present within the peanut extract.

 

Furthermore, some individuals with clinically insignificant or no sensitivity to allergens may have detectable levels of IgE antibodies in serum; therefore results must be interpreted in the clinical context. False-positive results for IgE antibodies may occur in patients with markedly elevated serum IgE (>2,500 kU/L) due to nonspecific binding to allergen solid phases.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Sicherer SH, Wood RA: Advances in diagnosing peanut allergy. J Allergy Clin Immunol Pract. 2013 Jan;1(1):1-13. doi: 10.1016/j.jaip.2012.10.004

2. Eller E, Bindslev-Jensen C: Clinical value of component-resolved diagnostics in peanut-allergic patients. Allergy. 2013 Feb;68(2):190-194. doi: 10.1111/all.12075

3. Homburger HA, Hamilton RG: Allergic diseases. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. Elsevier; 2017:1057-1070

4. Klemans RJ, van Os-Medendorp H, Blankestijn M, Bruijzeel-Koomen CA, Knol EF, Knulst AC: Diagnostic accuracy of specific IgE to components in diagnosing peanut allergy: a systematic review. Clin Exp Allergy. 2015 Apr;45(4):720-730. doi: 10.1111/cea.12412

Special Instructions Library of PDFs including pertinent information and forms related to the test