Allergies

Question: What is the difference between allergy and sinusitis?
Answer: Allergy is a specific way that your body reacts to certain foreign substances. For example, if you are allergic to dust mites, then when you breathe in "dustmite particles" they are recognized by specific allergy receptors in your nose. When they recognize the "intrusion" of dustmite particles, they cause the release of substances that are meant to fight the presence of these particles. These include the release of histamine and other substances that create an inflammatory response. These responses were designed as a defense against the "foreign intruder" -- that is to say, the dustmite particles. However, this allergy response has the unfortunate consequence of causing unpleasant symptoms such as a scratchy throat, watery eyes, runny nose, sneezing (to expel the intruder) and so forth. Therefore, we often take anti-allergy medicines to tone down this response and relieve the symptoms of allergy and allergic response.

If you have allergies, your nose may react to allergy-inducing substances in the air, such as dust or mold. Allergic nasal and sinus swelling may in turn lead to sinusitis.

Sinusitis is a bit more generic, it is simply inflammation in your nose and sinus cavities from any cause. Allergy can be one cause of inflammation, hence the term allergic rhinosinusitis, or sinusitis with an allergic component. However, there are a number of other factors that can contribute to sinusitis such as sensitivity to pollution, cigarette smoke, infection, and so forth.

Question: Is allergy common?
Answer: An estimated 20% of the United States population suffers from allergies. The nose is most commonly affected in the allergic individual. Symptoms include sneezing, itching of the eyes, nose, and throat, watery eyes, rhinorrhea, congestion, cough, and post-nasal drainage. An estimated 40 million Americans are afflicted with allergic rhinitis which in turn predisposes to many cases of sinusitis.

Question: Is there a simple test to tell if I have allergies?
Answer: A simple screening test that any doctor can perform is a complete blood count with differential. Elevation of a particular type of blood cell called EOSINOPHILS is suggestive of allergy. Measurement of serum immunoglobulins can also be diagnostic. Specifically, measurement of serum immunoglobulin type E is useful; elevated levels are suggestive of allergy.

More complicated tests include specialized blood tests for allergies and also the "skin scratch tests" with which many of you are familiar. These tests are described in this section.

Question: What are the treatments of allergy?
Answer: Avoidance of the allergic substances if possible. Environmental changes can be helpful, such as covering furniture, cleaning the house duct work, electrostatic air filters, and so forth. Medical therapy includes anti-histamines, mast cell stabilizers (cromolyn sodium) and also more generic anti-inflammatory agents such as nasal steroid spray. Immunotherapy (allergy drops or allergy shots) can also be helpful in specific cases.

Question: Tell me about immunotherapy.
Answer: These are the "shots" that a patient receives on a weekly basis that gradually immunizes them to the things that they are sensitive to. As the patient becomes more resistant to allergens, symptoms may subside.

Question: What is the role of allergy testing?
Answer: During a visit to the doctor, underlying allergies may be suspected in a patient who describes itchy or watery eyes, itchy nose, frequent sneezing, copious nasal drainage with nasal congestion, and itchy throat. These patients are often treated with topical nasal corticosteroid spray or cromolyn spray (Nasalcrom) and oral antihistamines. When these treatments fail, patients often undergo allergy testing.

Oral antihistamines are generally reserved for sinus patients with underlying allergies, because the drying effects of antihistamines may thicken secretions and can be otherwise detrimental in treating sinusitis. Patients with seasonal allergies should avoid pollens. Patients with perennial allergies should avoid exposure to dust, mold, and pet dandruff.

Question: Name three avoidance measures.
Answer: Determination of what you need to avoid may be accomplished by allergy testing. If you are allergic to your pets, you need to keep them out of your bedroom if you are not willing to give your pets away. With regard to this, there is a saying: "When a doctor tells a patient to 'get rid of their pet,' more often, the patient gets rid of their doctor!"

If you are allergic to dust mites, there are a number of measures that you can take including removal of rugs. There are special filters that can be placed over the air conditioning vents that will capture microscopic allergic particles.

If you have an old house that has built-in air ducts, these ducts should be professionally cleaned.

Finally, vacuum cleaners should be equipped with special microphore vacuum bags. These special vacuum bags trap small particles that cause allergy but that are not trapped by normal vacuum bags.

Question: What is the difference between seasonal and perennial allergies?
Answer: Allergic rhinitis is a hypersensitivity of the sinus and nasal mucosal membranes to allergens mediated through IGE antibodies. Allergic rhinitis may be classified as seasonal or perennial. Allergic rhinitis is considered seasonal when the symptoms occur only during specific periods of the year depending upon exposure to pollens. Ragweed, trees, and grasses are the most common sources of seasonal allergens. Allergic rhinitis is considered perennial when the symptoms occur for more than two hours a day for more than nine months. Dust mites, mold, and animal dander represent the most common sources of perennial allergens.

Question: Tell me about allergy testing.
Answer: The two recommended allergy testing options are serial end point titration, or SET, and radioallergosorbent test or RAST. Both SET and RAST give qualitative and quantitative information about the patient's response to specific allergens. The RAST test can be ordered by any doctor, but a specialty-trained allergist usually performs the SET and administers immunotherapy.

Question: Tell me about in vitro testing (RAST or radioallergosorbent test).
Answer: The RAST test involves a blood sample taken from the patient. A predetermined panel of allergens (allergic substances) are studied. The patient's blood is placed on special paper discs which have allergens bound to them. If the patient's blood has antibodies to these allergic substances, then the antibiodies will attach to them.

The discs are then washed so only bound antibodies remain. The disks are then treated with radioactively-labelled "anti-antibody" which will bind to any of the patient's antibodies present on the disc. A radiation counter will detect the presence of this radio-labelled antibody to allergic particles.

More recently, enzyme markers have replaced the radioactive labels. Results from RAST are then used to determine which allergens are responsible and guide immunotherapy. The results are also used to help calculate treatment doses.

RAST has the advantage of greater comfort and ease of testing for the patients. The in vitro test presents no risk of reaction by the patient. Medications and skin conditions will not affect RAST results.

RAST is slightly less sensitive and more expensive than SET. Both SET and RAST give qualitative and quantitative information that may be used for immunotherapy. They can safely be applied in the office setting and are valuable in the treatment of allergic rhinosinusitis.

Question: Tell me about serial end point titration.
Answer: Serial end point titration requires serial skin application of several dilutions of the allergen being investigated. When the patient is sensitive to a specific allergen the wheel will increase by at least 2mm with each increase of the dilution. The first dilution that leads to a 2mm increase is the end point, which is considered the safe starting dose for immunotherapy for that specific antigen. Subsequently, during immunotherapy the clinical response determines changes in dose.

Many clinicians who favor SET find that it has the advantage of providing immediate results. This allows immunotherapy to begin without any delay. The SET method involves testing suspected allergens based on the patient's history, therefore avoiding the need to do a large in vitro test panel as in RAST.

SET is found to be quite sensitive. Unlike RAST, SET results can be affected by antihistamines, tranquilizers, and antidepressants. For example, antihistamines must be discontinued at least 48 hours before SET. Skin conditions may also alter results because this method relies on skin application of allergen dilutions.

Food Allergies

Question: Tell me about food allergy.
Answer: Food allergy is increasingly recognized as a culprit in allergic disease. Cow's milk is the most common food allergen. Symptoms are usually gastrointestinal but may be similar to those related to inhalent allergy. Cyclic and fixed food allergies may occur.

The Cyclic type is more common, representing approximately 95% of food allergies. Symptoms related to cyclic food allergy will occur several hours after ingesting the allergenic food.

Fixed food allergies involve an immediate type of hypersensitivity reaction.