Complete and specific diagnosis of allergy is achieved by allergy tests. Comprehensive Allergy testing is aimed to establish the presence or absence of atopy (allergic tendency) and, to confirm the causative allergens and to establish the degree of their effect.
Allergy testing is the foundation for adopting measures to avoid exposure to causative allergens and in some cases to additionally consider the definitive treatment of Immunotherapy , which can help control the course of disease over a longer period of time.
The diagnosis of Allergic rhinitis is based upon the coordination between typical history of allergy symptoms and the findings on the diagnostic tests. Several types of specific allergic tests are available for allergy. The common ones used in clinical practice are either Blood Tests or Skin Prick Tests (SPT):
Total IgE. Though not specific, can be used to in certain situations toward diagnosis / ruling out allergic disease. It is also used to monitor the efficacy of Immunotherapy.
Specific IgE. (RAST). This is used to detect Allergen Specific IgE levels and one sample can be used to test for multiple allergens. While it is useful , it has its own limitations
Skin prick test (SPT)
SPT is the most convenient and clinically most useful method of allergy testing. It is considered to be the standard and very reliable method for testing for allergies. It also forms the foundation for possible Immunotherapy.
SPT is most commonly performed on the inner aspect of forearm, the upper arm and or the back. We first clean the skin with isopropyl alcohol. A small drop of testing allergen fluid is placed on your skin. Then, the skin is pricked through the drop. There’s a slight “prick” sensation when the testing is applied, but it doesn’t pain a lot.
After 15 minutes, the test site is checked for redness and swelling. Depending on the size of the wheal and erythema, the results of SPT can be graded into several categories. We can test for multiple allergens in one sitting.
The advantage of SPT is that it is minimally invasive and results are immediately available.
Some commonly used medicines like antihistamines and pain killer can interfere with SPT. If you are taking these medicines, they need to be stopped 5 to 7 days before skin test can be done. We will provide you with the complete information prior to the testing once you book your appointment for the SPT.
There are some other tests that may sometimes be asked for in certain situations to help with your overall treatment :
In some condition such as asthma and sinusitis , we may take the help of radiology such as CT scans or X-rays of the sinuses and chest, to get additional information.
Often you may be advised an Endoscopic examination of the nose and the nasopharynx visualize the inside of the nasal cavity to determine the extent of inflammation and to rule out other pathology.
Pulmonary function tests provide the functional status of the lungs and assist the chest physician in the management and monitoring of treatment.
Nasal secretion can be examined for the type of cells present (Cytology ). The procedure is simple and involves using a small sterile cotton-tipped applicator to swab the inside of the nose, collect secretion and study it under the microscope.