Diagnosis
Doctors have a wide range of tools at their disposal to make a correct diagnosis. This page describes the various forms of examination and tests.
Anamnesis
If you suspect that you have an allergy, you can visit your doctor, who will review your case history, which means that he or she will ask about your complaints. Your doctor will try to determine what is wrong and discuss your complaints with you. How is your overall condition? What exactly is the problem? When are your complaints the most severe and how long have they been bothering you? In addition, your doctor will check to see whether you have had allergic symptoms in the past. If there are signs that suggest that you have an allergy, you will undergo a physical examination.
Physical examination
A physical examination of the causes of an allergy focuses particularly on the facial skin and scalp (eczema), the eyes (redness) and the nose (blocked, runny, irritated mucous membrane). In addition, your doctor will listen to your breathing and examine the oral cavity and pharynx. There are all kinds of tests available to examine the causes of allergic reactions.
Intracutaneous tests
The doctor injects a minute amount of the substance that is suspected to trigger the allergic reaction, the allergen, into your skin. If the skin reddens and/or swells, you are sensitised to that substance.
Prick tests
The doctor checks for any allergic reactions by squeezing a drop of allergen extract (to which you are possibly allergic) on the skin of the forearm and then pricks the skin through the drop using a prick lancet.
Most of the allergic symptoms, such as a lump that may itch slightly, will appear after 15 minutes.
The treatment for the allergy will be determined on the basis of the patient's complaints and outcome of the tests.
Performing and interpreting a skin test.
If you are a medical professional and wish to know how a prick test is performed and interpreted, click here.
Blood tests
In addition to skin tests, blood tests also reveal the origin of the allergic reaction. For example, the 'RAST'(radio-allergo-sorbent test) method is used to measure the amount of IgE-antibodies against one allergen (grass pollen, for instance).
Provocation tests
During a provocation test, the allergen is brought into contact with the eye, nose or lungs. Any allergy to the allergen will reveal itself in the form of a reaction. Food allergy tests involve the administration of capsules containing different concentrations of allergen to determine whether a reaction occurs. Provocation tests are usually performed if the results of other tests are inconclusive.
Lung function test
Allergic symptoms may include constriction of the airways. If you visit your doctor with complaints about the airways, you may have to undergo a lung function test. It tests how the lungs work. How elastic are they? How sensitive are they? What is their volume? The test is also used to see how the lungs react to the administration of histamines, the substance released during an allergic reaction. This is called an aspecific provocation test.
Patch test (Epicutaneous test)
Patch tests are often used when a contact allergy is suspected. Small patches are applied to your back, each containing a different allergen. The result can be 'read' after about two days. If an eczema rash shows, you are sensitised to the allergen in question.
Exposure measurements
Exposure measurements are carried out to gain an understanding of the level of exposure to allergens. This may involve the collection of dust samples that are examined for quantities of allergen. Such an examination may be directed at all sorts of allergens: from house dust mites in mattresses and carpets to occupational allergens. In addition, air measurements can be performed to determine tree and grass pollen levels. These measurements are also used to broadcast pollen reports on the radio.
