Published: September 2025
Medically reviewed by:
Gary Falcetano, PA-C, AE-C
Peanut allergies can cause severe and life-threatening reactions, making accurate diagnosis and effective management essential. In this illustrative case study, we follow Tim, a young boy whose peanut allergy has significantly impacted his life. Despite careful avoidance, Tim suffered a concerning allergic reaction. This journey highlights the importance of specific IgE blood testing to aid in diagnosing the allergy and informing patient care.
Patient History
Tim, a 6-year-old with a presumed history of peanut allergy, visits his healthcare provider because he’s never been tested for allergen sensitization.
Tim’s healthcare provider conducts a full clinical history and physical examination and decides to test using whole peanut allergen with reflex to components.
Tim's personal history
- Tim experienced itching and tingling of the mouth and lips after eating a granola bar at age five.
- Tim’s parents assumed that the reaction was due to a peanut allergy.
- His previous healthcare provider recommended strict peanut avoidance.
Tim’s ImmunoCAP™ test results
These results together with this patient's case history and symptoms, help confirm the diagnosis.
ImmunoCAP specific IgE test results (kUA/l) |
||
Test* |
Type |
Tim's results |
Peanut |
Whole allergen |
1.6 kUA/l |
Ara h 1 |
Allergen component |
<0.1kUA/l |
Ara h 2 |
Allergen component |
<0.1kUA/l |
Ara h 3 |
Allergen component |
<0.1kUA/l |
Ara h 6 |
Allergen component |
<0.1kUA/l |
Ara h 8 |
Allergen component |
2.79 kUA/l |
Ara h 9 |
Allergen component |
<0.1kUA/l |
Product names: ImmunoCAP Allergen f13, Peanut, ImmunoCAP Allergen f422, Allergen component rAra h 1 Peanut, ImmunoCAP Allergen f423, Allergen component rAra h 2 Peanut, ImmunoCAP Allergen f424, Allergen component rAra h 3 Peanut, ImmunoCAP Allergen f447, Allergen component rAra h 6 Peanut, ImmunoCAP Allergen f352, Allergen component rAra h 8 PR-10, Peanut and ImmunoCAP Allergen f427, Allergen component rAra h 9 LTP, Peanut.
Differential diagnosis
Tim’s sensitization to Ara h 8 is associated with either no reactions or localized reactions, like itching and tingling of the mouth and lips, but low risk of systemic reaction. Tim may actually be sensitized to birch pollen, which is cross-reactive and responds similarly to Ara h 8. Tim shows no detectable sensitization to four nut storage proteins associated with severe reactions.1-3
Refined diagnosis
- Investigation of birch pollen allergy, as Tim also presents allergic rhinitis symptoms during the birch pollen season.
- This may indicate a primary sensitization to Bet v 1/PR-10 proteins and be consistent with cross-reactivity to Ara h 8.
Healthcare provider management plan
- Tim’s healthcare provider advises that an oral challenge with peanut might reduce the fear of severe reactions based on his history.
- Tim passes the peanut oral food challenge without any symptoms.
Follow-up
- Tim, with his mother, is seen by his healthcare provider one year later. Tim has had no further issues and is doing well.
Conclusion
Tim's case demonstrates the importance of accurate diagnosis and effective management of peanut allergies. ImmunoCAP Specific IgE tests helped his primary care provider to make an informed decision, enhancing his safety and quality of life.
The people, places and events depicted in these case studies and photographs do not represent actual patients, nor are they affiliated with Thermo Fisher Scientific.
Find out more about ImmunoCAP Specific IgE tests in food allergy.
