Allergy and intolerance
IgE antilichamen zalm
Antibodies against salmon protein; shows whether the immune system is sensitive to salmon, not whether you get symptoms from it.
Everything about this testWhat it measures
According to the Netherlands Nutrition Centre (Voedingscentrum), salmon is, together with tuna and cod, one of the most eaten kinds of fish in the Netherlands, fresh, smoked, canned and in sushi; fish must be listed as an allergen on food packaging. This test measures the amount of IgE antibodies against the proteins in salmon 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. Other kinds of fish, crustaceans and shellfish are not measured with this test.
- Sensitization to salmon: the body has made IgE antibodies against salmon
- Support in working out a suspected allergy to salmon, together with the history of the symptoms
High
A value above the cut-off means that you have IgE antibodies against salmon: sensitization. That is not the same as an allergy. Symptoms that fit an allergy are itching in the mouth and throat, hives, swelling of the lips, vomiting or shortness of breath, shortly after eating. According to Stichting Voedselallergie, different kinds of fish can contain different allergens; still, many people with a fish allergy react to more than one kind of fish. Crustaceans and shellfish contain other allergens; a result for salmon says nothing about them. 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 salmon were found. An IgE-mediated allergy to salmon is then much less likely. In two studies in the Dutch medical specialists' guideline (FMS), the IgE test for fish found 67 to 94 out of 100 people with a confirmed fish allergy, so occasionally a true allergy is missed. Other kinds of fish are not tested with this test. Symptoms after eating can also have another cause, for example an intolerance or a bowel condition.
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
Fish allergy is fairly rare: in Europe, an estimated 0.1 to 0.2 in 100 people have a fish allergy. According to Stichting Voedselallergie, fish allergy is more common in adults than in children and usually does not go away, unlike allergy to milk or egg.
Who is this useful for
Useful with a clear reaction shortly after eating salmon, such as itching or swelling in the mouth and throat, hives, vomiting or shortness of breath. According to Stichting Voedselallergie, breathing in fumes while fish is being fried can also cause airway symptoms in sensitive people. In people who eat salmon normally without symptoms, the test adds nothing, and with vague symptoms without a clear link to a meal, it adds little.
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: Vis
- Voedingscentrum: Vis
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