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HelpTest Code BLWRF Walnut-Food, IgE, with Reflex to Walnut-Food Components, 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: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Useful For
Evaluation of patients with suspected walnut-food allergy
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| BLWX | Walnut-Food Components, IgE, S | No | No |
Testing Algorithm
Testing begins with analysis of walnut-food-specific total IgE. If walnut-food-specific total IgE result is negative (<0.10 kU/L), testing is complete.
If walnut-food-specific total IgE result is 0.10 kU/L or more, then walnut-food component (Jug r 1 and Jug r 3) testing will be performed at an additional charge.
Special Instructions
Method Name
Fluorescent Enzyme Immunoassay (FEIA)
Reporting Name
Walnut-Food Component Reflex, SSpecimen Type
SerumSpecimen Minimum Volume
0.6 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 14 days | |
| Frozen | 90 days |
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 walnut-food IgE antibody is present (≥0.10 IgE kUa/L), additional specific component IgE antibody testing will be performed. If at least one potential specific allergenic walnut-food component IgE is detectable (≥0.10 IgE kUa/L), an interpretive report will be provided.
When the sample is negative for total walnut-food IgE antibody (<0.10 IgE kUa/L), further testing for specific walnut-food component IgE antibodies will not be performed. Negative IgE results for total walnut-food antibody may indicate a lack of sensitization to potential walnut-food allergenic components.
Clinical Reference
1. Salo PM, Arbes SJ Jr, Jaramillo R, et al. Prevalence of allergic sensitization in the United States: results from the National Health and Nutrition Examination Survey (NHANES) 2005-2006. J Allergy Clin Immunol. 2014;134(2):350-359
2. Waserman S, Watson W. Food allergy. Allergy Asthma Clin Immunol. 2011;7 Suppl 1(Suppl 1):S7
3. Abrams EM, Sicherer SH. Diagnosis and management of food allergy. CMAJ. 2016;188(15):1087-1093
4. Weinberger T, Sicherer S. Current perspectives on tree nut allergy: a review. J Asthma Allergy. 2018;11:41-51
5. Lomas JM, Jarvinen KM. Managing nut-induced anaphylaxis: challenges and solutions. J Asthma Allergy. 2015;8:115-123
6. Maloney JM, Rudengren M, Ahlstedt S, Bock SA, Sampson HA. The use of serum-specific IgE measurements for the diagnosis of peanut, tree nut, and seed allergy. J Allergy Clin Immunol. 2008;122(1):145-151
7. Sicherer SH, Burks AW, Sampson HA. Clinical features of acute allergic reactions to peanut and tree nuts in children. Pediatrics. 1998;102(1):e6
8. Crespo JF, James JM, Fernandez-Rodriguez C, Rodriguez J. Food allergy: nuts and tree nuts [published correction appears in Br J Nutr. 2008 Feb;99(2):447-8]. Br J Nutr. 2006;96 Suppl 2:S95-S102
9. Yang L, Clements S, Joks R. A retrospective study of peanut and tree nut allergy: Sensitization and correlations with clinical manifestations [published online ahead of print, 2015 Feb 27]. Allergy Rhinol (Providence). 2015;doi:10.2500/ar.20105.6.0108
10. Pastorello EA, Farioli L, Pravettoni V, et al. Lipid transfer protein and vicilin are important walnut allergens in patients not allergic to pollen. J Allergy Clin Immunol. 2004;114(4):908-914
11. Rosenfeld L, Shreffler W, Bardina L, et al. Walnut allergy in peanut-allergic patients: significance of sequential epitopes of walnut homologous to linear epitopes of Ara h 1, 2 and 3 in relation to clinical reactivity. Int Arch Allergy Immunol. 2012;157(3):238-245
12. Masthoff LJ, Hoff R, Verhoeckx KC, et al. A systematic review of the effect of thermal processing on the allergenicity of tree nuts. Allergy. 2013;68(8):983-993
13. Costa J, Carrapatoso I, Oliveira MB, Mafra I. Walnut allergens: molecular characterization, detection and clinical relevance. Clin Exp Allergy. 2014;44(3):319-341
14. Valcour A, Lidholm J, Borres MP, Hamilton RG. Sensitization profiles to hazelnut allergens across the United States. Ann Allergy Asthma Immunol. 2019;122(1):111-116.e1
15. Asero R, Piantanida M, Pravettoni V. Allergy to LTP: to eat or not to eat sensitizing foods? A follow-up study. Eur Ann Allergy Clin Immunol. 2018;50(4):156-162
Day(s) Performed
Monday through Friday
Report Available
Same day/1 to 3 daysPerforming 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 |
|---|---|---|
| BLWRF | Walnut-Food Component Reflex, S | 6273-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| BLW1 | Walnut-Food, IgE, S | 6273-7 |
Forms
If not ordering electronically, complete, print, and send an Allergen Test Request (T236) with the specimen.