Allergy and intolerance
IgE antilichamen bijvoet
Antibodies against pollen from mugwort, a weed; shows whether the immune system is sensitive to this pollen, not whether it bothers you.
Everything about this testWhat it measures
Mugwort (Artemisia vulgaris) is a weed that grows widely along roads, on verges and on wasteland and flowers in late summer. This test measures the amount of IgE antibodies against mugwort pollen in the blood, in kU/l. IgE is the type of antibody that, in an allergic reaction, triggers mast cells to release histamine; the body only makes these antibodies after it has previously been in contact with the allergen, and this is called sensitization.
- Sensitization to mugwort: the body has made IgE antibodies against mugwort pollen
- Support in working out hay fever symptoms in late summer, together with the history of the symptoms
High
A value above the cut-off means that you have IgE antibodies against mugwort pollen: sensitization. That is not the same as an allergy. In people with symptoms such as sneezing, a blocked or runny nose, itchy or watery eyes or shortness of breath in late summer, a positive result fits hay fever from weed pollen; according to the Longfonds (Dutch lung foundation), weeds such as mugwort and ragweed cause symptoms from July to September. 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 mugwort pollen were found. Hay fever from mugwort is then much less likely. Symptoms in late summer can also come from grass pollen at the end of the season, from mold spores or from other weeds such as ragweed. Nasal symptoms can also have a non-allergic cause.
If your result is abnormal
The GP mainly looks at the history: in which months and where the symptoms occur. With a positive result and matching symptoms, advice follows to reduce contact with pollen, such as keeping windows closed on dry, sunny days, and if needed medication for the nose and eyes. With a lot of symptoms despite medication, an allergist or ENT specialist can discuss immunotherapy, where the result for single allergens helps determine which pollen it targets.
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; the result therefore only means something if it fits when and where you have symptoms. With mugwort, late summer is an important part of that history: symptoms that fit the flowering of weeds make a positive result more meaningful. 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.
- The test only measures mugwort; ragweed and other weeds are not measured, although antibodies against related weeds can cross-react.
- The result says little about the severity of the symptoms; a higher value does not automatically mean more trouble.
- Laboratories use different measurement methods and cut-off values; results from different labs cannot be compared one to one.
How common is this
Hay fever is common and often starts at a young age. Allergy to weed pollen such as mugwort is less common than allergy to grass or tree pollen; according to the Longfonds (Dutch lung foundation), weeds cause symptoms from July to September. Sensitization is more common than the allergy itself.
Who is this useful for
Useful with symptoms of the nose, eyes or airways that come back every year in late summer, from July to September, especially outdoors. In people without such symptoms, the test adds nothing: sensitization without symptoms is not a disease and is not treated.
Downsides and risks
- A positive result without symptoms can cause unnecessary worry or unnecessary measures, while sensitization without symptoms does not need treatment.
- A normal result does not rule out symptoms in late summer from other pollens or molds.
Sources
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