An allergy test is an investigative procedure that is used in the diagnosis of an allergy. The body is tested for so-called allergens, i.e. substances that are suspected of triggering the allergic symptoms in the person's body.
- Medication or also
- include infectious agents.
Sensitization, i.e. a sensitive reaction, as well as an allergy, i.e. to a substance that triggers a specific allergic reaction, can be determined. Therapy can then be recommended depending on the result.
Indications for an allergy test
An allergy test should always be carried out if an allergy is suspected. Therefore, if signs occur, a doctor should be consulted in order to diagnose or rule out a possible allergy.
The signs of an allergy include, first of all, a temporal relationship between the symptoms in relation to a certain situation or a certain substance, for example the appearance of a rash after eating a certain food. The symptoms can manifest themselves in different parts of the body. If there is a regular rash on the skin, the formation of blisters and itching, a doctor should be consulted. Swelling, i.e. edema, can also be a possible symptom of an allergy. Furthermore, signs such as nausea or vomiting, diarrhea or constipation should be taken into account. The eyes can also be affected. The conjunctiva may itch or become inflamed. In addition, the nose and nasal mucous membranes are often itchy.
If one or more of these symptoms are observed, a doctor should be consulted and an allergy test performed.
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The course of an allergy test
In general, an allergy test uses various methods to check whether there is an allergy to a certain substance.
It can be measured whether there are antibodies against this substance in the body, which are there to fight it, since the body classifies them as "toxic". This is usually done when there is already a specific suspicion of an allergy, for example to a food. All that is required for this is a blood sample, which is then examined in a special laboratory for said antibodies and other parameters relevant to the severity of the allergy.
Another method is to bring the potential allergen (i.e. the allergy-causing substance) into direct contact with the body and to observe or measure the body's reaction to it. With this type of test, the allergen is usually not known exactly, e.g. with hay fever. The best known test for this is the prick test, in which the allergens are applied to the skin next to one another and the reaction is observed after a small incision.
Are there any risks with an allergy test?
Depending on the type of allergy test, it can be associated with different risks. With the simple allergy blood test there are usually no other risks other than the usual blood sample.
However, if an allergy test is carried out in which the body is brought into direct contact with an allergy-causing substance (allergen), a severe allergic reaction can occur in rare cases. However, this occurs very rarely because the body is exposed to a very small amount of an allergen when performing the test. If such an allergic reaction does occur, in severe cases it can lead to impaired circulation and anaphylactic shock. Therefore, this type of allergy test should only be performed under medical supervision. In an acute, life-threatening situation, the doctor is prepared for possible complications and can identify them quickly and treat them safely by providing an emergency kit.
In some cases, a delayed allergic reaction can occur, especially in the case of an allergy test if a food allergy is suspected. Therefore, if possible, this type of allergy test should be performed in the hospital, as the late allergic reaction when performed in a practice is unlikely to occur until after leaving the practice.
A skin prick test is a common way to determine if you have an allergy. This is a skin test that can be carried out very easily in a practice and only takes about half an hour. It is usually done on the forearm on the palm side.
When carrying out the test, various possible allergens, i.e. substances that could be the cause of the allergy, are applied next to one another to the skin of the person to be tested. Then a lancet, a kind of small sharp knife, is used to make a minimally small cut in the center of each applied sample. If there is an allergic reaction, reddening and wheals appear on the skin. Wheals are punctiform raised areas of the skin. In addition, a sample of common salt is applied as a negative control and a sample of histamine as a positive control for each prick test. This means that normally no skin reaction occurs with table salt and wheals always occur with histamine. In this way, the various reactions to the other test allergens can be compared with one another and their intensity can be downgraded.
More on this subject: Prick test
Which doctor does the allergy test?
Since a large number of people are affected by allergies, there are now more and more doctors who can do an allergy test.
Depending on the type of allergy test, a different number of specialists or specialties offer this type of allergy test. Allergists, i.e. specialists who mainly treat patients with various allergies, specialize in allergy tests. Furthermore, various allergy tests can be carried out by doctors specializing in pulmonology, i.e. pulmonologists (pulmonologists).
If it is a matter of simple allergy tests, such as a blood sample, this can also be done by a normal family doctor. If there is a suspicion of an allergy and the wish for an allergy test, the family doctor can be asked about this in all cases. If necessary, the family doctor will refer the person concerned if the allergy is too specific and special equipment is required for the allergy test.
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Can you do an allergy test to drugs?
An allergy test against medication is a very complex procedure that is always carried out in a clinic under medical supervision. The test usually only takes place if there is a specific suspicion of an allergy to a drug.
The affected person is given the drug in the way it should normally be given, usually either as a tablet or as an injection into a vein. The body's reaction to the drug is then observed and, in the event of an allergic reaction, counteracted immediately. This type of allergy test is called a provocation test. Unfortunately, there is usually no low-risk method of testing an allergy to a drug. Negative exposure is usually preferred, i.e. allergy testing to a drug that is not expected to cause an allergic reaction.
If an allergy to a drug is found, this is noted in an allergy passport. Doctors can find precise information about the drug here so that it can be avoided in the future. When performing an allergy test against medication, it should always be borne in mind that severe allergic reactions can occur. It is therefore important to think carefully beforehand whether it is really useful and necessary to carry out this test.
What do you do with the results of the allergy test?
With an allergy test, depending on the type of allergy test, different results can come out, which can have different degrees of relevance and impact for the patient. If the result of an allergy test is not clear, it should be carried out again after weighing up the risks and benefits. It should always be kept in mind that the diagnosis of an allergy means a restriction on the patient's everyday life.
If the diagnosis of an allergy is confirmed in an allergy test, this is discussed in detail with the person concerned. It is important that the person concerned understands that further exposure (i.e. exposure) to the allergen (i.e. allergy-causing substance) can lead to a severe, potentially life-threatening allergic reaction of the body. In addition, an allergy passport is created in which the allergy is noted. This allergy pass should always be carried by the person concerned. In the case of an allergy to medication, in particular, it is important that this is known quickly in an emergency. Furthermore, depending on the allergy, various therapy options are discussed with the person concerned.
When carrying out a blood test to determine an allergy, the focus is on the detection of specific antibodies.
This is usually the so-called "IgE value". These are antibodies, i.e. substances that are produced by the body in order to fight the supposedly "bad" allergen, i.e. the substance that triggers the allergy. Depending on the severity of the allergy, the IgE value also varies. In addition, so-called inflammation parameters are determined in the blood. An allergy is an inflammatory reaction in the body that is associated with an increase in certain levels, such as CRP (C-reactive protein). However, these values are not indicative of an allergy.
Is there also an allergy test for at home?
If an allergy is suspected, an allergy test can be carried out on the internet before visiting a doctor at home.
Specific questions are answered that can reinforce the suspicion of an allergy and the substance causing the allergy. However, this type of allergy test cannot confirm a diagnosis. Therefore, if symptoms occur that suggest an allergy, a doctor should be consulted for further clarification. Of course, it can make sense to inform them of the result of the allergy test previously carried out at home.
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Duration of an allergy test
An allergy test can take different lengths of time, depending on how it is carried out.
If a blood test is done for certain antibodies or other substances in the blood, it usually only takes 5-10 minutes. The results are usually sent within 1-2 weeks by the responsible laboratory.
A prick test takes about half an hour. First of all, after applying the allergens, i.e. allergy-triggering substances, you have to wait about 15-20 minutes for the body to react. The allergy test is then evaluated.
What does an allergy test cost?
An allergy test has different costs depending on the type of test and the place where it is carried out or the person who offers the allergy test. Usually the cost of an allergy test is between around 50 and 150 euros.
If there is a specific suspicion of an allergy, the costs are usually covered by the statutory or private health insurance. It must be clear that the allergy is causing symptoms for the person concerned. In the case of an allergy test that should be carried out in a clinic, for example if an allergy to medication is suspected, the costs are correspondingly higher. They depend on how long the person concerned stays in the clinic and are usually also covered by the health insurance company. If there is any uncertainty about the assumption of the costs, the responsible health insurance company should be consulted again before the test is carried out.
What role does histamine play in an allergy test?
Histamine is a naturally occurring tissue hormone in the body that plays an important role in an allergic reaction. This means that it acts as an intermediary and plays an important role in various processes of the immune system. The severity or severity of an allergic reaction depends, in addition to a few other factors, on the amount of histamine released in the body by the allergen, i.e. the substance that triggers the allergy.
In a prick test or other skin test, the reddening and formation of blisters after the allergen is applied correlates directly with the amount of histamine released in the body. In addition, in the prick test, histamine itself is always used as an allergen in order to carry out a positive control. This means that when the prick test is carried out with histamine as the allergen, there is usually always a minor allergic reaction in the form of reddening and blistering. This can serve as a reference to compare other allergens and the severity of the allergic reactions they cause.
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Can you do an allergy test on babies and does it make sense?
An allergy test can also be carried out at an early age.
It is common that most of the time a skin test is not done on a child younger than 4 years old. This is because if anaphylactic shock occurs despite the low risk, it is more difficult to treat in children. In addition, this can often have more serious consequences than with an adult. A skin test is often carried out on young children during an operation, for example a dental treatment that takes place under anesthesia, in order to save the children as much suffering as possible. With babies, a blood test to check for an allergy can only take place after a sufficient cost-benefit assessment.
It makes a lot of sense that an allergy test is carried out on a child as early as possible so that an allergy diagnosed as a result can be recognized early and treated appropriately.
Can you do an allergy test during pregnancy?
In principle, it is possible to carry out an allergy test during pregnancy.
If a pregnant woman is suspected of having an allergy, she should consult a doctor to have it diagnosed. However, only blood tests are performed during pregnancy. A skin prick test or other skin test has a minimal risk of an extremely severe allergic reaction including anaphylactic shock. In order to prevent this risk, a skin test to diagnose an allergy is usually not carried out during pregnancy.
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