Allergy Testing: Why Seafood Isn't Always the Culprit

Q: Allergy Testing: Why Seafood Isn't Always the Culprit

Dear Ms. <br>CoCo： <br>Although allergen testing is frequently conducted, it often yields results that are difficult to explain. <br>This is primarily because the tests typically use a limited selection of representative allergens and do not encompass all possible allergens. <br>

Allergy

Hello Doctor,
I would like to ask about my recent allergy testing (which included allergens such as oranges, almonds, brewer's yeast, and egg yolk).
I have previously experienced allergic reactions to seafood and assumed I was allergic to it.
However, the test results indicated that I am not allergic to seafood.
What could be the reason for this? Thank you for your response!

CoCo, 20~29 year old female. Ask Date: 2009/09/03

Dr. Cai Mengru reply Family Medicine

Dear Ms.
CoCo:
Although allergen testing is frequently conducted, it often yields results that are difficult to explain.
This is primarily because the tests typically use a limited selection of representative allergens and do not encompass all possible allergens.
It is possible that you are indeed allergic to certain seafood, but those specific seafood items may not be included in the test.
Given that there are countless environmental allergens, it is challenging to fully represent them with a single test.
However, positive test results are generally quite reliable and can serve as a reference for adjusting your living environment.

Sincerely,
Dr.
Tsai Meng-Ju, Family Medicine Department, Taoyuan Hospital

Reply Date: 2009/09/03

More Info

Understanding allergy testing can be quite complex, especially when personal experiences do not align with test results. In your case, you have a history of allergic reactions to seafood, yet your recent allergy test did not indicate a sensitivity to it. This discrepancy can arise from several factors.

Firstly, it’s important to understand that allergy tests, such as skin prick tests or blood tests measuring specific IgE antibodies, are designed to detect the presence of an immune response to specific allergens. However, these tests may not always capture the full picture of an individual's allergic profile. For instance, the tests may not include all possible allergens, or they may not be sensitive enough to detect certain reactions. Additionally, some individuals may have what is known as a "non-IgE-mediated" allergy, which means their allergic reactions do not involve the typical IgE antibodies that most allergy tests measure. This could explain why you experienced reactions to seafood in the past, but the tests did not confirm an allergy.

Another possibility is that your seafood allergy may have been a result of cross-reactivity. This occurs when the proteins in one substance are similar to those in another, leading the immune system to react to both. For example, if you are allergic to certain proteins in shellfish, you might also react to other foods with similar proteins, but this does not necessarily mean you are allergic to all seafood.

Moreover, it’s also worth considering that allergies can change over time. Some individuals may outgrow certain food allergies, while new allergies can develop. If you have been consuming seafood without issues recently, it may indicate that your immune system has adapted, or that your previous reactions were due to other factors, such as the method of preparation or the specific type of seafood consumed.

In your case, it would be beneficial to keep a detailed food diary, noting what you eat and any reactions you experience. This can help you and your healthcare provider identify patterns and potential triggers. Consulting with an allergist or immunologist can provide further insights and possibly recommend additional testing or an oral food challenge, which is a controlled way to determine if you have a food allergy.

In summary, the reasons for the discrepancy between your allergy test results and your personal experiences with seafood can include the limitations of allergy testing, the possibility of non-IgE-mediated reactions, cross-reactivity, and changes in your immune response over time. It is essential to work closely with a healthcare professional to navigate these complexities and ensure your safety regarding food allergies.

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