If you believe you have allergies, it makes sense to find out what your allergies are. Locating a doctor who specializes in allergy (Allergist) in Malaysia is not an easy task as there are only a handful doctors who offer the service.

Allergy tests today are more convenient and accurate than before. Before we go into the various tests available, its important to understand these two terms:

Sensitized: means your body is 'primed' to an allergen. A positive skin test therefore indicates that you are sensitized to the allergen while you may not necessarily have the allergic symptoms. Confused? This means that you may test positive for peanuts by allergy test; although you have never developed any allergic symptoms to peanut before. In another words, sensization to peanuts means you have the potential to develop peanut allergy in the future, even if you never had peanut allergy. More confused? Read on and I will explain.

Allergy: means definite reaction to allergen. This means when the doctor says you are allergic to peanuts (as an example), eating peanuts will surely provoke allergic symptoms (itchy rash, puffy face and eyes or choking).

The interpretation of allergy test to identify the offending allergen is best left to allergist or doctors trained in allergy - to avoid any misinformation. An allergist is trained to distinguish between a sensitization and a true allergy by taking a careful allergy history and interpreting the allergy test. In addition, the allergist is to treat a person with multiple allergies involving different organs. A patient may be suffering from skin, dust and food allergies at the same time and it is important to identify and treat all the allergies simultaneously.

Now, lets talk about the different allergy tests.

Allergy testing involve skin and/or blood test to identify allergens that is causing your allergy. Allergy test can be broadly classified into two groups, namely Skin Prick Test and Blood Test.

Skin Prick Test

Skin Prick Tests (SPT) can be done as an outpatient procedure in an allergy alinic. This is the most preferred test method as the results can be known in 15 to 20 minutes and its cheaper than blood tests.

The SPT comes in a kit form with small bottles of laboratory prepared allergens. The doctor selects the allergens to be tested (usually up to 10 allergens ) and apply a very tiny drop of the allergen on your forearm. The doctor then makes a tiny needle prick on the skin surface through the applied allergen drop (don't be afraid-it does not hurt as the needle rest only on the skin surface). There is usually no blood seen during the test.

Each suspected allergen is tested by individual pricks. Usually up 10 allergens can be tested on a single sitting. A small swell at the site of the needle prick ( more than 3mm diameter) within 15 minutes is said to be a positive test for that allergen. (image below).

Remember: These tests only denotes sensitization and not necessarily allergy.

Another modified skin prick test is called the prick-prick test which is usually done for fresh food or fruits. A small slice of the food is pricked with the needle before pricking onto the skin. A swelling at the site may indicate allergy to the said fruit.

Blood Test : The Rast or Immunoabsorbant assay

This test involves drawing blood from the forearm and dispatching it to labs that do allergy testing. After a couple of days , the results will indicate the level of antibody for the tested allergens. The allergen specific antibody called IgE (Immunonoglobulin) will be raised if your are sensitive to the allergen. Again, this is a sensitization test- a high level IgE is indicative of sensitization but not necessarily allergic to the allergen.

Patch Test

Patch test is usually done to detect contact dermatitis. This includes testing for metal, chemical, leather and latex allergies.There are a few types of test kits available in the market. It comes with a standard of 10-20 common pre-filled metals, chemicals and other materials that commonly causes skin allergies such as eczemas and dermatitis. These are then applied to the back of the torso and left for 24-48 hours before reading for reactions. The stronger the reaction the more pronounced is the redness. Sometimes, the reactions can be so strong that it causes a bleb or a wound at the site. The patient is usually warned to remove the patch if there is pain.

The type or the quantity of test selected by the allergist is dependent on the disease; based on a good clinical history and medical examination. A consent is a must before any test can be performed.

Next chapter: What are your treatment options?