Allergy and intolerance
IgE antilichamen huisstofmijt (D. farinae)
Antibodies against the house dust mite species D. farinae; shows whether the immune system is sensitive to this mite, not whether it bothers you.
Everything about this testWhat it measures
House dust mites are tiny creatures that live in mattresses, pillows, furniture and carpets and feed on skin flakes; the proteins in their droppings cause the symptoms. There are two common species: Dermatophagoides pteronyssinus and Dermatophagoides farinae. The standard house dust mite test measures D. pteronyssinus, the species most common in Dutch homes; D. farinae is more common in regions with a drier climate. The proteins of both species are very similar. This test measures the amount of IgE antibodies against D. farinae in the blood, in kU/l.
- Sensitization to the house dust mite D. farinae: the body has made IgE antibodies against this mite
- An addition to the standard house dust mite test with symptoms that are present all year round, especially indoors and in bed
High
A value above the cut-off means that you have IgE antibodies against D. farinae: sensitization. That is not the same as an allergy. With symptoms that are present all year round, such as a blocked or runny nose, sneezing, itchy eyes or shortness of breath indoors, a positive result fits a house dust mite allergy. Because the two species are very similar, the result of the standard house dust mite test is usually positive as well; the measures against house dust mite are the same for both species. In people without such symptoms, a positive result only means that the antibodies are there; no treatment follows.
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: when and where the symptoms occur, and whether there is also asthma or eczema. With a positive result and matching symptoms, advice follows on having less house dust mite in the home, especially in the bedroom, and if needed medication for the nose or airways. If the symptoms are not brought under control with this, a referral to an ENT specialist, lung specialist or allergist may follow, where immunotherapy may also be discussed.
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
House dust mite allergy is one of the most common allergies in the Netherlands and causes symptoms that are present all year round. Sensitization is more common than the allergy itself: some people with antibodies have no trouble from them.
Who is this useful for
Useful with symptoms that are present all year round and are worse indoors, especially in bed or when dusting and tidying. Because the two house dust mite species are very similar, this test usually adds little to the standard house dust mite test; it can help if that result is unclear. In people without such symptoms, the test adds nothing: sensitization without symptoms is not a disease and is not treated.
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
- Thuisarts.nl: Ik wil iets doen tegen huisstofmijt
- FMS Richtlijnendatabase: Allergie van de bovenste luchtwegen, module Klinische diagnostiek
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