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Diagnostic work-up and treatment in allergology

The last few decades have seen a definite rise in allergic disorders, particularly those involving the skin and mucous membranes. However, not everything labeled “allergy” really is a true allergy. Through detailed patient history (interviewing the patient) and suitable diagnostic measures, the allergologist attempts to identify whether the hypersensitivity is allergic or non-allergic in nature because this distinction allows appropriate recommendations for  its prevention and treatment.

Diagnostic work-up in allergology

Allergies require previous handling of and contact with substances (known as allergens) which may trigger allergies. Today, the face-to-face allergologic interview of the patient by the physician substantiating or ruling out such an allergen still is the most important measure. This interview quite often yields valuable insight into allergens which might be considered possible or can be eliminated.

Once the patient history has already outlined possible triggers of the allergic manifestations, the decision is made whether additional diagnostic steps are required and if so which measures.

Our office is equipped with a broad range of modern diagnostic facilities pertinent in allergy work-up.

Blood panels in allergology (serologic antibody screening)

We perform the following blood tests:

  • Total IgE and specific IgE
  • Fast check (a test requiring only a few drops of blood from the finger tip), particularly in infants/toddlers
  • IgG
  • Imu Pro

These blood tests can identify antibodies against a wide range of allergens (pollen, animal hair, food products, medication, latex, mites, fungi, etc.).

Skin testing

Prick test
The prick test is used in so-called type 1 allergy.

Type 1 allergy means that the allergic reaction becomes manifest within seconds or at most minutes after contact with the allergen. Characteristic type 1 allergies include allergic conjunctivitis (inflammation of the conjunctiva), allergic rhinitis (running/clogged nose), allergic asthma, hives (urticaria), laryngeal edema, but also major or life-threatening types such as angioneurotic edema (Quincke edema) and anaphylactic shock.

In diagnostic work-up of type 1 allergies, solutions of the purified allergens are dribbled onto the skin which is then (painlessly) pricked with a small lancet, thereby creating contact between the inside of the body and the allergen. In case of type 1 allergies, the patient will demonstrate reddening, hives and itching within minutes. The result is assessed after 20 minutes. The test is particularly useful to detect not only the presence of inhalation allergies (pollen, house dust, animal hair, molds), food allergy and insect venom allergy, but also latex allergy.

Prick to prick testing
Prick to prick testing is used in the diagnostic work-up of food allergies (testing with the suspected food). After first pricking the raw food with the specific prick test lancet the latter is then used to prick the skin on the lower arm, while the food is left on the skin. Allergic reactions appear as reddening, hives and itching. The result is assessed after 20 minutes.

Rub testing
Rub testing is used in the diagnostic work-up of food allergies. The raw food, after moistening if necessary, is rubbed under light pressure into a circumscribed area on the inside of the lower arm. Allergic reactions appear as reddening, hives and itching. The result is evaluated after 20 minutes.

Intracutaneous testing
Intracutaneous testing is used in the diagnostic work-up of insect venom allergies and medication allergies (e.g., pain killers, local anesthetics). During intracutaneous testing a small amount of allergen solution is injected into the topmost layer of the skin. This test is far more sensitive than prick testing because a significantly larger amount of allergen comes into direct contact with the immune system of the skin; however, intracutaneous testing is only possible for a certain range of medications.

Conjunctival/nasal provocation testing
This test becomes necessary only if skin testing or blood tests have not confirmed the presence of allergens although an allergic root problem is still suspected (e.g., mite allergy, pollen allergy). Here, a heavily diluted allergen solution is dribbled into the conjunctival sac of the eye or into the nose. The allergic reaction will appear after a few minutes as itching and reddening of the eyes, increased nasal secretions or a clogged nose.

Subcutaneous provocation testing:
This test comes into play when intolerance to local anesthetics is suspected. First, various local anesthetics are subjected to prick and intracutaneous testing. If these tests are negative (i.e., no reaction at the area tested) a standardized amount of local anesthetics primarily regarded as uncritical (or even the suspected local anesthetic itself) is injected under the skin. If the local anesthetic is tolerated, this is recorded in an allergy record card and this medication can be used in future procedures.

Epicutaneous testing
Epicutaneous testing is performed to diagnose contact allergies. In contact allergies (type 4 allergy) the allergic reaction of the skin does not appear directly after administration of the allergen, but only after a certain delay of one to three days. Contact eczema (= contact allergy) is an acute or chronic inflammation of the outermost layer of the skin (epidermis) triggered by external contact substances and is accompanied by reddening and formation of nodules, blebs and scales and varying degrees of itching. Frequently, contact eczema is triggered by metals (nickel, cobalt, potassium dichromate), fragrances in ointments, cosmetics, preservatives (e.g., parabens etc.), ointment base (e.g., wool grease alcohols), hair dyes (e.g., paraphenylenediamine), etc.

On test day 1, a number of suspected allergens contained in a base (e.g., vaseline) are applied on the back in small separate airtight (occlusive) aluminium chambers. The adhesive strip is removed after 24 hours and a first assessment performed regarding any reaction (reddening, welts, infiltration) at the test site. The second assessment takes place after another 48 hours. If one or more contact allergens have been identified, the patient will be issued an allergy record card detailing not only the allergens but also precise information on their occurrence and spread.

There are numerous test series of certain allergens on the market containing the most common allergy triggers. Depending on the problem at hand, there are test blocks for, e.g., fragrances and preservatives, ointment base, hair products, dental substances, metals, medication, etc.

Physical testing in hives:
In hives (= urticaria) the skin demonstrates fleeting itchy reddening and swelling (welts) similar to the reaction when coming into contact with stinging nettles. If during the interview the patient’s history raises the suspicion of physically triggered urticaria, i.e., constitutionally conditioned discharge of welt producing substances in the skin induced by rubbing (factitious urticaria), pressure (pressure urticaria), cold (cold urticaria), heat (heat urticaria), exertion (cholinergic urticaria) or ultraviolet light (light urticaria), detailed diagnostic work-up will include a variety of physical tests (dermographism, cryobath, heat testing, pressure testing, light testing).

Treatment in allergology

In desensitization (also known as specific iummunotherapy or hyposensitization) the body slowly adapts to the allergen triggering the allergy. It is used in patients allergic to insect venom (bee or wasp venom), as well as in patients with hay fever or asthma caused by type 1 allergy against pollen, house dust, mold spores or animal hair. Desensitization in patients with hay fever can avert allergic asthma and prevent the reemergence of other allergies. In standard subcutaneous desensitization minute amounts of the allergen are injected in slowly increasing doses under the skin of the upper arm; in general, the treatment takes at least 3 years (for insect venom usually 5 years). In certain cases so-called sublingual desensitization (by means of drops administered underneath the tongue) is also possible. The so-called “grass tablet” is used in hay fever triggered by grass/grain pollen; here, the allergen is administered as a tablet slowly dissolving underneath the tongue.

In desensitization success depends on the type of allergy. Resolution of or marked improvement in the symptoms is seen in 95% of insect allergy cases, with this rate decreasing to 80%-90% in pollen allergy and 70%-80% in mite allergy.