Do You Need to Repeat Allergy Testing After Five Years?

Q: Do You Need to Repeat Allergy Testing After Five Years?

Hello, thank you for your question. <br>Here are my responses： <br>1) I still have some allergic symptoms, but I'm not sure what the allergens are. <br>Is it necessary for me to undergo the 36-item allergen test again? Generally speaking, is there a high probability that somethin

Do allergens need to be tested repeatedly?

Hello, Doctor Gao: I am 21 years old this year and have had an allergic constitution since childhood.
When I was 16, I underwent allergen testing (M25-130-Z MAST ALLERGY) at Chang Gung Memorial Hospital, which tested 36 allergens, all of which returned a value of 0 (Non-Detectable).
I would like to ask the doctor: 1) I still experience some allergic symptoms but do not know the specific allergens.
Is it necessary for me to retest these 36 allergens? Generally speaking, is there a significant chance that substances that were not allergens five years ago could become allergens after five years? 2) Additionally, when I was 11, I also underwent a limited allergen test at Chang Gung, which included only six allergens.
The dust mite value was 0.53 (class 1), the dog dander value was 0.36 (class 1), and the other four values ranged from 0.01 to 0.06 (class 0).
These values did not have units.
Based on this information alone, can we conclude that I am allergic to dust mites and dog dander? Thank you, Doctor.

Hao, 20~29 year old female. Ask Date: 2023/05/15

Dr. Gao Jiankai reply Internal Medicine

Hello, thank you for your question.
Here are my responses:
1) I still have some allergic symptoms, but I'm not sure what the allergens are.
Is it necessary for me to undergo the 36-item allergen test again? Generally speaking, is there a high probability that something that was not an allergen five years ago could become one now? --> There are many mechanisms of allergies, and testing for allergens is just one method to assess the allergic mechanism.
In principle, it is best to confirm that the IgE allergy index is elevated before testing for allergens, as this increases the likelihood of identifying abnormalities.
If the IgE test is normal, allergen testing is usually not necessary.
Additionally, there are other methods for allergen testing besides the 36-item MAST test, which can be arranged if necessary, but again, the prerequisite is that the IgE must be elevated to easily detect abnormalities.
2) When I was 11 years old, I underwent an allergen test at Chang Gung Hospital that included only 6 allergens.
The dust mite value was 0.53 (class 1), and the storage mite value was 0.36 (class 1), while the other 4 values ranged from 0.01 to 0.06 (class 0).
These values were provided without units.
Based on this information, can I say that I am allergic to dust mites and storage mites? --> The test values need to be interpreted in conjunction with symptoms for a more accurate assessment.
Common symptoms of dust mite allergy typically include respiratory symptoms such as rhinitis and asthma, rather than skin itching and hives.
Furthermore, even if one is allergic to dust mites, this allergy often diminishes over time, so there is no need to worry too much.

Best regards from the Allergy, Immunology, and Rheumatology Department of Changhua Hospital, Ministry of Health and Welfare.

Reply Date: 2023/05/15

More Info

When it comes to allergy testing, the question of whether to repeat tests after a significant period, such as five years, is a common concern for many individuals, especially those with a history of allergic reactions. In your case, having undergone allergy testing at the age of 16 and receiving non-detectable results for 36 allergens, it is understandable that you are questioning the necessity of retesting, especially since you are now experiencing some allergic symptoms.

1) Need for Retesting: It is generally advisable to consider retesting if you are experiencing new or worsening allergic symptoms, even if previous tests showed no detectable allergies. Allergies can develop at any point in life, and it is possible for substances that were previously non-allergenic to become problematic over time. The immune system can change, and new sensitivities can emerge, particularly in response to environmental changes, lifestyle factors, or even hormonal changes. Therefore, if you are experiencing symptoms that you suspect are related to allergies, repeating the allergy testing could provide valuable insights into your current sensitivities.

2) Understanding Previous Results: Regarding your earlier tests at age 11, where you had low values for dust mites (0.53 for dust mites and 0.36 for cockroach allergens), these results indicate a very low level of sensitization (Class 1). While these values suggest that you are not significantly allergic to these allergens, they do not completely rule out the possibility of having a mild sensitivity. The classification system typically ranges from Class 0 (no sensitization) to Class 6 (high sensitization), and a Class 1 result indicates a low level of sensitization. It is important to note that even low levels of sensitization can lead to allergic reactions under certain circumstances, especially if exposure is frequent or if other factors (like respiratory infections or environmental changes) are present.

In summary, if you are experiencing new allergic symptoms, it would be prudent to consult with an allergist or a healthcare provider about retesting. They can help determine the most appropriate tests based on your current symptoms and history. Additionally, they may recommend specific strategies for managing your symptoms, which could include avoidance of known allergens, medications, or even immunotherapy if appropriate.

In conclusion, while your previous tests showed no significant allergies, the development of new symptoms warrants a reevaluation. Allergy testing is not static; it reflects a snapshot of your immune system's response at a given time. Therefore, staying proactive about your health and seeking further evaluation can lead to better management of your allergic conditions.

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