Allergy and intolerance
IgE antilichamen hazelnoot
Antibodies against hazelnut protein; shows whether the immune system is sensitive to hazelnut, not whether you get symptoms from it.
Everything about this testWhat it measures
In the Netherlands, hazelnut is, together with walnut, the nut that most often causes an allergy. Nuts are also found in, for example, bread, cookies and salads, and sometimes in cosmetics; hazelnut must be listed as an allergen on food packaging. This test measures the amount of IgE antibodies against the proteins in hazelnut 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 hazelnut: the body has made IgE antibodies against hazelnut
- Support in working out a suspected allergy to hazelnut, together with the history of the symptoms
- A possible explanation for itching or a burning feeling in the mouth or throat after eating hazelnut in people with hay fever from birch pollen
High
A value above the cut-off means that you have IgE antibodies against hazelnut: sensitization. That is not the same as an allergy. In three studies in the Dutch medical specialists' guideline (FMS), between about 1 in 4 and more than 8 in 10 of the people without a hazelnut allergy still tested positive, often due to a cross-reaction with birch pollen: a protein in hazelnut closely resembles a protein in birch pollen. With hay fever, this can cause itching or a burning feeling in the mouth or throat after eating hazelnut (oral allergy syndrome). For nuts, the FMS guideline still recommends further testing for such mouth symptoms after a small amount, because a larger amount can cause a severe reaction and mouth symptoms can be the start of one. In case of doubt, an allergist can have antibodies against individual hazelnut proteins measured; these say more about the chance of a severe reaction than the level of this result.
Low
A value below the cut-off means that no IgE antibodies against hazelnut were found. An IgE-mediated allergy to hazelnut is then much less likely, although it is not completely ruled out: in three studies in the Dutch medical specialists' guideline (FMS), the test found 75 to 99 out of 100 people with a hazelnut allergy. Other nuts and peanut are not tested with this test. Symptoms can also 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, 1 to 2 in 100 people in the Netherlands have a nut allergy, both children and adults; hazelnut and walnut top the list. Part of this is a milder form linked to hay fever from birch pollen, with mainly symptoms in the mouth and throat. Someone who reacts to one type of nut often also reacts to other nuts.
Who is this useful for
Useful with a clear reaction shortly after eating hazelnut, such as hives, swelling, vomiting or shortness of breath, or with mouth symptoms after a small amount of hazelnut. Someone with hay fever who has often eaten larger amounts of hazelnut with only mild itching in the mouth usually needs no further testing, according to Thuisarts.nl and the FMS guideline. In people who eat hazelnut 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: Noten
- 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