Process
A microscopic amount of an allergen is introduced to a patient's skin by various means:
- Prick test or scratch test: pricking the skin with a needle or pin containing a small amount of the allergen.
- Patch test: applying a patch to the skin, where the patch contains the allergen
If an immuno-response is seen in the form of a rash, urticaria (hives), or (worse) anaphylaxis it can be concluded that the patient has a hypersensitivity (or allergy) to that allergen. Further testing can be done to identify the particular allergen.
The "scratch test" as it's called, is still very commonly used as an allergen test. A similar test involving injecting the allergen is also used, but is not quite as common due to increased likelihood of infection and general ineffectiveness by comparison. There are other methods available to test for allergy.
Some allergies are identified in a few minutes but others may take several days. In all cases where the test is positive, the skin will become raised, red and appear itchy. The results are recorded- larger wheals indicating that the subject is more sensitive to that particular allergen. A negative test does not mean that the subject is not allergic; simply that either the right concentration was not used or the body failed to elicit a response.
Read more about this topic: Skin Allergy Test
Famous quotes containing the word process:
“Any balance we achieve between adult and parental identities, between children’s and our own needs, works only for a time—because, as one father says, “It’s a new ball game just about every week.” So we are always in the process of learning to be parents.”
—Joan Sheingold Ditzion, Dennie, and Palmer Wolf. Ourselves and Our Children, by Boston Women’s Health Book Collective, ch. 2 (1978)
“Science is a dynamic undertaking directed to lowering the degree of the empiricism involved in solving problems; or, if you prefer, science is a process of fabricating a web of interconnected concepts and conceptual schemes arising from experiments and observations and fruitful of further experiments and observations.”
—James Conant (1893–1978)
“I believe that history might be, and ought to be, taught in a new fashion so as to make the meaning of it as a process of evolution intelligible to the young.”
—Thomas Henry Huxley (1825–95)