Shrimp IgE
Shows whether your immune system has made IgE antibodies to shrimp. This is called sensitization and doesn't always mean a shrimp allergy.
AI-verified against cited sources. Awaiting expert reviewAlso called f24, F024LOINC 6246-3
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What it is
Shrimp is a crustacean shellfish and one of the major food allergens. This test measures IgE, the antibody type linked to allergic reactions, that your body has made against shrimp. The main shrimp allergen is a muscle protein called tropomyosin. It survives cooking, and it is very similar in crab, lobster, house dust mites and cockroaches. That is why a positive shrimp result can come from dust mite or cockroach sensitization rather than from shrimp itself. Sensitization means your body has made IgE antibodies to a substance. It does not always mean you are allergic.
Why it matters
Shellfish allergy can cause reactions that range from itching in the mouth, hives and stomach upset to a serious reaction called anaphylaxis, and it tends to last into adulthood. A positive shrimp result shows that IgE is present. It does not prove you are allergic, because IgE to shrimp can come from mite or cockroach sensitization. A negative result also doesn't fully rule out an allergy. Your history of reactions matters most, and an allergy specialist may use a supervised food challenge to settle the question.
If it’s high
A result above your lab's usual range means your body has made IgE antibodies to shrimp. It is more likely to match a true shrimp allergy if you have had symptoms soon after eating shrimp. The number alone can't tell how strong a reaction would be, and no blood test can predict how severe a future reaction will be.
Common causes
- A true shrimp allergy, with symptoms soon after eating shrimp
- Sensitization without symptoms, which is common with food IgE tests
- Cross-reaction with tropomyosin from house dust mites or cockroaches, so a positive result can reflect mite or cockroach sensitization
- Cross-reaction with other shellfish such as crab and lobster, and less often with mollusks such as clams and oysters, which share tropomyosin
- A weak result of 0.10 to 0.34 kU/L, which labs treat as uncertain
What can help
- If you have had symptoms after eating shrimp, talk with your clinician before eating it or other shellfish again
- Ask whether dust mite or cockroach sensitization could explain your result, and whether an allergy specialist should review it
- Ask about hidden sources, since dried shrimp or shrimp paste can be in some soups and instant noodles
- Ask for a written plan for what to do if you have a reaction
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: Labcorp, ARUP Laboratories, Quest Diagnostics, Thermo Fisher Scientific (Phadia), NIAID / Journal of Allergy and Clinical Immunology, Allergo Journal International, Journal of Allergy and Clinical Immunology, MedlinePlus (National Library of Medicine).
ImmunoCAP class scale as printed by Quest and ARUP (labs differ on which class an exact edge value falls in)
- Class 0: absent or undetectablebelow 0.1 kU/L
- Class 0/1: very low level, relevance uncertain0.1 to under 0.35 kU/L
- Class 1: low level0.35 to under 0.7 kU/L
- Class 2: moderate level0.7 to under 3.5 kU/L
- Class 3: high level3.5 to under 17.5 kU/L
- Class 4: very high level17.5 to under 50 kU/L
- Class 5: very high level50 to under 100.01 kU/L
- Class 6: very high level100.01 and above kU/L
Labcorp class scale (ImmunoCAP, as printed on Labcorp reports)
- 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 100.01 kU/L
- Class VI: very high100.01 and above kU/L
What can affect your result
- House dust mite and cockroach sensitization: they share tropomyosin with shrimp, and cockroach and shrimp IgE clustered together in a US survey
- Other shellfish (crab, lobster, clams, oysters): IgE to one often cross-reacts with others, but reactions when eating them vary
- Cooking: tropomyosin is heat-stable, so cooking does not remove it
- Lab method: results from different labs or assay systems may not be comparable
- IgE to tropomyosin from house dust mites or cockroaches can contribute to a positive shrimp result without shellfish allergy (Thermo Fisher; NIAID 2010).
- Results from different labs and test brands are not directly comparable, so compare results from the same lab and method (NIAID 2010).
- Labs may reject samples that are hemolyzed (red cells broken), jaundiced (icteric) or lipemic (very fatty). ARUP lists all three as unacceptable.
- MedlinePlus notes that some medicines, such as antihistamines, may matter before an allergy blood test. Tell your clinician about everything you take and ask them what applies to you.
Antibody levels usually change slowly, over months to years.
When to talk to a clinician
Call your local emergency number if, soon after eating shrimp or other shellfish, you have trouble breathing, throat tightness, swelling of the lips or tongue, repeated vomiting, dizziness or fainting. See a clinician soon if you get hives, itching or stomach upset after eating shrimp or other shellfish.
Questions you could ask
- How should I read this result if I've never had a reaction to shrimp?
- Does this result fit the symptoms I've had after eating shrimp?
- Could my dust mite or cockroach allergy explain this result?
- Should I see an allergy specialist, and would testing for other shellfish help?
- Is a supervised food challenge appropriate for me?
- What should my plan be if I have a reaction?
Questions people ask
If my shrimp result is positive, do I have to avoid all shellfish?
Not necessarily. Shrimp, crab and lobster share the same main protein, so IgE to shrimp often shows up for them too, but reports vary on how often people also react when they eat them. Reactions to mollusks such as clams and oysters are less common among people allergic to shrimp. An allergy specialist can test and, if it makes sense, supervise safe trials. If you have had a reaction, talk with your clinician before trying other shellfish.
I'm allergic to dust mites. Why is my shrimp test positive?
Dust mites, cockroaches and shrimp all contain tropomyosin, a very similar protein. IgE made against the mite or cockroach version can bind the shrimp version in the lab. That can make the shrimp result positive without telling you whether shrimp gives you symptoms. Your clinician or an allergy specialist can help sort out whether it matters for you.
Can I have a negative result and still be allergic?
It's uncommon, but yes. Undetectable IgE can happen in people with an IgE-mediated food allergy. If your history strongly suggests a reaction, your clinician may suggest a supervised food challenge before you eat the food again.
Show the science and sources
Units
- 1 kU/L = 1 kU/L
- 1 kU/L = 1 UA/mL
For clinicians and researchers
ImmunoCAP f24 is a fluorescent enzyme immunoassay for IgE to a shrimp extract (ARUP's aliases name Pandalus borealis, Penaeus monodon and other species). The major shrimp allergen is tropomyosin (Pen a 1 / Pen m 1), a heat-stable invertebrate panallergen. Arginine kinase (Pen m 2), myosin light chain (Lit v 3) and sarcoplasmic calcium-binding protein (Pen m 4) are other allergens. Tropomyosin cross-reacts with other crustaceans, mollusks, house dust mite (Der p 10, Der f 10) and cockroach, so extract IgE can reflect mite or cockroach sensitization instead of shellfish allergy; Pen a 1 and Der p 10 component tests are separate catalog markers. In the NIAID 2010 summary table, shrimp versus other crustacea showed IgE cross-reactivity in 50% to 100% and clinical reactivity in about 38% of studied patients (not systematically confirmed by blinded challenge), and crustacea versus mollusks showed 47% IgE and about 14% clinical cross-reactivity. In one study of 92 shrimp-allergic patients, 71.4% were sensitized to Pen a 1. NHANES 2005-2006 included shrimp (Pandalus borealis) and found it clustered with German cockroach IgE. Sensitization alone does not define food allergy, and undetectable IgE occasionally occurs in IgE-mediated food allergy, so a supervised oral food challenge remains the reference standard.
LOINC 6246-3 (primary), 112200-1. Specimen: serum.
Sources
- F024-IgE Shrimp (test 602473), Labcorp
- Sample patient report: F024-IgE Shrimp (test 602473), Labcorp
- Allergen, Food, Shrimp (test 0055030), ARUP Laboratories
- ImmunoCAP Specific IgE Blood Test: Allergy Test List (interpretation table and test codes), Quest Diagnostics (2017)
- Your quick guide to using ImmunoCAP Specific IgE testing, Thermo Fisher Scientific (Phadia)
- Allergen Encyclopedia: f24 Shrimp, Thermo Fisher Scientific (Phadia)
- Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of the NIAID-Sponsored Expert Panel, NIAID / Journal of Allergy and Clinical Immunology (2010)
- Allergens and molecular diagnostics of shellfish allergy: Part 22 of the Series Molecular Allergology, Allergo Journal International (2016)
- Prevalence of allergic sensitization in the United States: results from the National Health and Nutrition Examination Survey (NHANES) 2005-2006, Journal of Allergy and Clinical Immunology (2014)
- Allergy Blood Test, MedlinePlus (National Library of Medicine)
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.