Skin testing

Skin testing is an in vivo method of identifying the presence in an individual of specific IgE to a given allergen.25 It is useful for both clinical practice and research purposes. Clinically it is used to supplement the patient's history and examination. Reactions to specific allergens will guide the clinician as to the specific substance that has caused or is causing the patient's problem. If the patient had a life-threatening reaction and the results of the skin prick test are concordant with the patient's clinical history, the clinician and patient may opt to take no further diagnostic action, and simply avoid the particular foodstuff. More commonly, however, the clinical history and skin test results are not sufficient. There may be positive skin tests without a confirmatory history, or a suspicious history with negative skin tests. This calls for the use of the doubleblind placebo-controlled challenge to confirm or negate any suspicions that may have arisen from the history and examination or skin tests, in particular to prevent the potentially nutritionally and certainly socially harmful effects of an unnecessarily restricted diet.

Skin tests are simple, readily available, rapidly performed and inexpensive. They have the disadvantage of producing a significant number of false positives and false negatives, especially when improperly performed. They rely upon the presence within the skin of all the necessary cells and mediators for the occurrence of a Type I hypersensitivity reaction. A small amount of allergen is introduced percutaneously. An immediate weal-and-flare reaction (see below) is provoked in the patient's skin. This is dependent upon proinflammatory and neurogenic mediators. Histamine and tryptase are released by mast cell degranulation after the introduction of allergen, recognised by specific IgE. Histamine is the major mediator of the weal-and-flare reaction. The immediate reaction occurs about 15-20 minutes after the test, and is used as evidence of a positive reaction. Visual evidence of this reaction is oedema (the swollen weal) and erythema (the surrounding red flare). The patient will often also complain that the area itches.25

There are two main methods of performing skin tests: the prick-puncture and the intradermal method. The main issues surrounding their use are their diagnostic utility, and their respective levels of comfort and safety.

How To Deal With Rosacea and Eczema

How To Deal With Rosacea and Eczema

Rosacea and Eczema are two skin conditions that are fairly commonly found throughout the world. Each of them is characterized by different features, and can be both discomfiting as well as result in undesirable appearance features. In a nutshell, theyre problems that many would want to deal with.

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