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Blood Test Tracker

Cashew Nut IgE

Measures IgE antibodies to cashew nut to show whether your immune system has become sensitized to it.

AI-verified against cited sources. Awaiting expert reviewAlso called f202, F202LOINC 6718-1

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What it is

This test measures IgE, the antibody type involved in allergic reactions, against cashew nut (ImmunoCAP f202). Cashew belongs to the same plant family as pistachio and mango. Results come in kilounits per liter (kU/L), and many labs also print a class from 0 to 6. Some labs automatically add a second test for Ana o 3, a main cashew allergen, when this result is about 0.10 kU/L or higher.

Why it matters

In people who are allergic, cashew can cause reactions from hives and stomach upset to anaphylaxis. A positive result alone does not show that you are allergic, because many people have antibodies to nuts they eat without any trouble. Cashew and pistachio are closely related, so antibodies to one often show up for the other. The result is most useful alongside your history of reactions.

If it’s high

A level above the 'none detected' range means the lab found IgE antibodies to cashew. This is called sensitization. It is not the same as an allergy, and the number cannot tell you how severe a reaction would be. Higher levels make a reaction more likely, but your history, and sometimes a supervised food challenge, is what shows whether you are allergic. Your clinician can put the result in context.

Common causes

  • Sensitization to cashew with no reaction when it is eaten
  • IgE that cross-reacts with pistachio or other tree nuts
  • Cashew allergy

What can help

  • Talk with an allergist about what this result means for you, including whether pistachio and other nuts are safe
  • Ask whether an Ana o 3 component test or a supervised food challenge would add clarity
  • Ask your clinician before adding nuts to the diet or removing them because of a number

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

For adults: 0–0.09 kU/L. Source: ARUP Laboratories, Labcorp, Children's Minnesota Laboratory, Thermo Fisher Scientific (Phadia), Allergy, American Academy of Pediatrics (Pediatrics).

ImmunoCAP IgE classes (ARUP, Iowa, Children's Minnesota and CUHK; labs differ on which class an exact edge value falls in)

  • Class 0: no significant level detectedbelow 0.1 kU/L
  • Class 0/1: clinical relevance undetermined0.1 to under 0.35 kU/L
  • Class 1: low0.35 to under 0.7 kU/L
  • Class 2: moderate0.7 to under 3.5 kU/L
  • Class 3: high3.5 to under 17.5 kU/L
  • Class 4: very high17.5 to under 50 kU/L
  • Class 5: very high50 to under 100 kU/L
  • Class 6: very high100 and above kU/L

Labcorp class scale (cutoffs differ from the ImmunoCAP scale above; exactly 100.00 is class V)

  • Class 0: negativebelow 0.1 kU/L
  • Class 0/I: equivocal or low0.1 to under 0.32 kU/L
  • Class I: low0.32 to under 0.56 kU/L
  • Class II: moderate0.56 to under 1.41 kU/L
  • Class III: high1.41 to under 3.91 kU/L
  • Class IV: very high3.91 to under 19.01 kU/L
  • Class V: very high19.01 to under 100 kU/L
  • Class VI: very high100 and above kU/L

What can affect your result

  • Related nuts and plants, especially pistachio, which can cause cross-reacting IgE
  • Eczema, asthma and other allergies, which often occur together with food sensitization
  • The lab and test brand, because results from different systems are not directly comparable
  • Antihistamines generally don't interfere with blood IgE tests, unlike skin tests (AAP). MedlinePlus advises telling your provider about everything you take, since some medicines may matter for this test, so ask your clinician before changing any medicine.
  • Assays from different manufacturers aren't equivalent, so compare results only from the same lab and method (AAP).

Slow. IgE levels usually shift over months to years, not weeks.

When to talk to a clinician

Get urgent medical help for trouble breathing, swelling of the lips, tongue or throat, repeated vomiting, widespread hives, dizziness or fainting after eating nuts. Otherwise, talk with a clinician before eating cashew if you have had any reaction to it, even if this result is low.

Questions you could ask

  • Which lab method was used, and should I use the same lab for future results?
  • Does this result match any reaction I have had to cashew?
  • Would an Ana o 3 test or a supervised food challenge help?
  • Do I also need to be careful with pistachio or other nuts?
  • Does a low result mean I can eat cashew, or do we need more testing?

Questions people ask

What is the Ana o 3 test my lab added?

Ana o 3 is one of the main proteins in cashew that triggers allergic reactions. Some labs add it automatically when the cashew result is about 0.10 kU/L or higher. In one study of children it separated cashew-allergic from cashew-tolerant children better than the whole-cashew test.

If I react to cashew, do I also need to avoid pistachio?

Cashew and pistachio are closely related and often cross-react, but not everyone who reacts to one reacts to the other. An allergist can advise based on your history and tests, so ask before trying pistachio.

What do the class numbers 0 to 6 mean?

The class groups the kU/L number from none detected (class 0) to very high (class 6). Higher classes mean more antibody and a higher chance of a reaction, but not a more severe one. Labcorp's class cutoffs differ from the ones ARUP and many hospital labs use, so compare the kU/L number rather than the class between labs.

Show the science and sources

For clinicians and researchers

Quantitative IgE to a cashew nut (Anacardium occidentale) extract (ImmunoCAP f202) by fluoroenzyme immunoassay; ARUP and Labcorp both use the ImmunoCAP system, which reports about 0.1 to 100 kUA/L. Results from the different FDA-cleared IgE systems are not equivalent (AAP 2012). Ana o 3 (f443), a 2S albumin, is one of three major cashew allergens (with Ana o 1, a vicilin, and Ana o 2, a legumin). In a multicentre study of 61 children evaluated for cashew allergy (42 allergic, 19 tolerant), Ana o 3 IgE separated allergic from tolerant children better than cashew extract IgE (area under the curve 0.94 vs 0.78), and a 95% probability of allergy was estimated at 2.0 kU/L for Ana o 3 (Lange 2017). That is one pediatric cohort on the ImmunoCAP system, not a universal cutoff. ARUP (test 3018562) adds Ana o 3 when the cashew result is 0.1 kU/L or higher, and Labcorp (profile 604159) adds it when the result is above 0.10 kU/L. Thermo Fisher describes extensive cross-reactivity with pistachio, and mango, sumac and pink peppercorn belong to the same plant family. Higher sIgE reflects the likelihood of a reaction, not its severity (AAP 2012). ARUP reports 0.10 to 0.34 kU/L as 'clinical relevance undetermined'.

LOINC 6718-1 (primary), 112155-7. Specimen: serum.

Sources

  1. Allergen, Food, Cashew With Reflex to Components, IgE (test 3018562), ARUP Laboratories
  2. Cashew Nut (test 602461), Labcorp
  3. Allergen Profile, Cashew Nut, IgE With Component Reflex (test 604159), Labcorp
  4. Sample report 607120, Allergens with Component Reflexes Area 20 (class description table), Labcorp
  5. Allergen (IgE) ImmunoCAP, University of Iowa Hospitals & Clinics, Pathology Handbook
  6. Allergen IgE (laboratory test information), Children's Minnesota Laboratory
  7. Immunoglobulin E (IgE, Allergen-Specific), Serum, Chinese University of Hong Kong, Prince of Wales Hospital ward manual
  8. Your quick guide to using ImmunoCAP Specific IgE testing, Thermo Fisher Scientific (Phadia) (2024)
  9. Allergy Testing in Childhood: Using Allergen-Specific IgE Tests (clinical report), American Academy of Pediatrics (Pediatrics) (2012)
  10. Allergy Blood Tests, MedlinePlus (National Library of Medicine)
  11. Allergen Encyclopedia: Cashew nut (f202), Thermo Fisher Scientific (Phadia)
  12. Ana o 3-specific IgE is a good predictor for clinically relevant cashew allergy in children, Allergy (2017)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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