Allergy and intolerance
IgE antilichamen appel
Antibodies against apple protein; often fits a cross-reaction with hay fever from birch pollen. Does not say whether you get symptoms.
Everything about this testWhat it measures
Apple is widely eaten, raw and processed in, for example, pies and sauces. A reaction to apple can come from a cross-reaction: a protein in apple closely resembles a protein in birch pollen, so the immune system of people with hay fever from birch pollen also recognizes apple. This test measures the amount of IgE antibodies against the proteins in apple in the blood, in kU/l. The body only makes these antibodies after it has previously been in contact with the allergen; this is called sensitization.
- Sensitization to apple: the body has made IgE antibodies against apple
- Support in working out a suspected allergy to apple, together with the history of the symptoms
- A possible explanation for itching or a burning feeling in the mouth or throat after eating raw apple in people with hay fever from birch pollen
High
A value above the cut-off means that you have IgE antibodies against apple: sensitization. That is not the same as an allergy. With hay fever from birch pollen, a positive result often fits oral allergy syndrome: itching, tingling or a burning feeling on the lips, mouth or throat shortly after eating raw apple. According to Thuisarts.nl, these symptoms are not dangerous and go away on their own; heated apple usually causes no symptoms. Hives, abdominal symptoms or shortness of breath after apple fit such a cross-reaction less well; the Dutch medical specialists' guideline (FMS) then always recommends a food challenge, and an allergist can have antibodies against individual apple proteins measured. The level of the value says little about how severe a reaction would be.
Low
A value below the cut-off means that no IgE antibodies against this allergen were found. An IgE-mediated allergy to this allergen is then much less likely, although it is not completely ruled out. Symptoms can also come from another allergen that was not tested, or have a non-allergic cause.
If your result is abnormal
The GP mainly looks at the history: which symptoms, when and where they occur and after contact with what. With a positive result and matching symptoms, advice usually follows to limit contact with the allergen and, if needed, medication. With a severe reaction, in case of doubt or with symptoms that are not brought under control this way, a referral to an allergist, pediatrician, ENT specialist or lung specialist may follow.
Reliability
A positive IgE result shows sensitization, not allergy: it only says that there are antibodies, not that you get symptoms from them. The Dutch medical specialists' guideline (FMS) on upper airway allergy says this literally and recommends choosing a test for single allergens based on the history of the symptoms; for food allergy, the FMS guideline on food challenge testing calls the history of the symptoms the cornerstone of diagnosis and a food challenge in hospital the gold standard. The result therefore only means something if it fits when, where and after contact with what you get symptoms. A positive result without symptoms is not treated.
Limitations
- Sensitization without symptoms is common; the result can only be interpreted together with the history of the symptoms.
- Related allergens can recognize each other's antibodies (cross-reaction), for example pollen and nuts or fruit; a positive result then does not mean that this particular allergen causes the symptoms.
- The test measures all proteins from the allergen source together; testing for individual proteins (components) can say more in case of doubt.
- Laboratories use different measurement methods and cut-off values; results from different labs cannot be compared one to one.
How common is this
According to Stichting Voedselallergie, 300,000 to 400,000 people in the Netherlands are bothered by an apple allergy, one of the most common forms of food allergy. With a cross-reaction with birch pollen, the symptoms are usually mild. According to Thuisarts.nl, such symptoms occur in older children and adults.
Who is this useful for
With only mild itching or a burning feeling in the mouth after raw apple in someone with hay fever, no testing is needed according to Thuisarts.nl, and you can keep eating apple. The test says more with other or more severe symptoms after apple, such as swelling, hives, abdominal symptoms or shortness of breath, as an addition to the assessment by the doctor. In people who eat apple normally without symptoms, the test adds nothing.
Sources
- NVKC, allesovertesten.nl: Allergie (RAST)
- FMS Richtlijnendatabase: Allergie van de bovenste luchtwegen, module Aanvullende diagnostiek
- FMS Richtlijnendatabase: Voedselprovocatie, module Plaatsbepaling diagnostiek voedselallergie
- Thuisarts.nl: Ik heb allergie
- NHG-Standaard Voedselovergevoeligheid en coeliakie (M47)
- Stichting Voedselallergie: Appel
- Thuisarts.nl: Ik krijg jeuk of een branderig gevoel in mijn mond of keel door sommige groenten, fruit of noten
- Thuisarts.nl: Ik heb hooikoorts
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results