How are allergies diagnosed?
There are a number of ways in which allergies can be accurately diagnosed. Firstly, the doctor will ask the patient to describe his or her symptoms and if they occurred after exposure to a certain substance in order to determine what their allergens are. After which, a physical examination will be performed.
For example, a rash on a person’s hands may denote that they have come into contact with latex gloves and therefore, they may be allergic to latex. This type of allergy will be diagnosed as allergic contact dermatitis (ACD).
If someone has a food allergy, they may know exactly what causes the reaction, for example, nuts often elicit a serious allergic reaction that is blatantly obvious.
If, however, this is not the case, the doctor may ask the patient to keep a list of the foods eaten (known as a food diary) and what causes a reaction. A process of elimination may also be introduced through eliminating certain foods from one’s diet in an attempt to determine what specific foods are allergens. After the elimination, certain food groups will then be introduced back into the diet to figure out what is causing the reaction.
When allergies are suspected, a doctor is likely to also refer the patient to a specialised allergist for skin testing. In a skin test, the allergist (also sometimes performed by a doctor or nurse) pricks the skin, typically the skin on the inside of the patient’s arm, after which, the allergist will expose a small amount of proteins that are found in substances that have been identified as potential allergens to the pricked area. The reaction of the skin is documented. An allergic reaction to the allergen which the skin has been exposed to, results in the skin forming a rash, becoming red or inflamed.
The doctor or allergist may also conduct a blood test. This is known as a radioallergosorbent test, abbreviated as RAST. This tests the patient’s blood to determine whether there are antibodies present in response to the allergens. These are known as immunoglobin E allergens. A blood sample will be taken and sent to a laboratory for results.