The diagnosis of allergic rhinitis is made by nasal endoscopy and allergy tests in patients with symptoms compatible with allergy. Symptoms of allergic rhinitis; runny nose, sneezing, tearing, nasal congestion, cough, itching in the throat and nose, postnasal drip. Endoscopic examination of the nose in patients with symptoms compatible with allergy may reveal edematous nasal mucosa, swollen nasal meats, and a white discharge. The tests used in the further diagnosis of allergic rhinitis are skin tests, nasal provocation tests, laboratory tests and nasal smear. The most used test is the prick test because of its advantages such as being simple, inexpensive, easy to apply and reliable.
In the Prick test, known as the skin test, a drug containing allergens is dripped onto the patient’s forearm with an applicator. After half an hour, the swelling in the forearm is evaluated and the test is concluded. However, for this test to give an accurate result, some drugs must be discontinued beforehand. These drugs are antihistamines used orally in allergies, some depression drugs and creams containing topical cortisone applied to the skin. Antihistamines and antidepressants should be discontinued seven days before, and creams three weeks before the test. The test may also be positive in people who do not have allergy symptoms. The positivity of the test does not make the diagnosis of allergy. A positive test in people with allergy symptoms makes the diagnosis of allergic rhinitis. Prick test is a painless and practical method. Very rarely, a systemic reaction called anaphylaxis may occur in the person who is tested, but this rate is very rare.
Another test to diagnose allergic rhinitis is to look for specific IgE in the blood. Specific IgE means IgE produced specifically for that substance against an allergic substance in the blood. For example, if a person has a house dust allergy, house dust specific IgE means specific IgE produced against house dust. Measuring these substances can help in the diagnosis of allergic diseases. However, the diagnosis is not made just by looking at these test results. Serum specific IgE measurement can be made in the blood if the patients are taking drugs that reduce the response of the skin, if there is any skin disease, if the person being tested has a risk of anaphylaxis or if the patient cannot cooperate with the skin test. Specific IgE can be measured against approximately 600 substances in the blood. This method is more expensive than the Prick test.
Total IgE measurement may be normal in approximately 50% of allergic patients. The total amount of IgE is high and the patient may not have atopy. Total IgE level is increased in viral infections, smokers, lymphoma and paracytosis. In studies, it has been determined that the probability of atopy is around 33% in cases where the total IgE amount is below 10 IU / ml, and the rate of atopy rises to 99% in cases where this value is above 400 IU / ml.A less common method is the number of eosinophils in the nasal secretions. A finding in favor of allergic rhinitis in the diagnosis is that the number of eosinophils above 20% or the amount of mast cells is more than 3% in the nasal smear. In a nasal provocation test with a specific allergen, more than 100% increase in resistance, more than 5 sneezes, and more than 0.5 ml increase in secretion are considered positive.
Prof. Berna Uslu Coskun MD