An<unk>  testing machine being operated in a diagnostic immunology lab Effective management of<unk> c diseases relies on the ability to make an accurate diagnosis.<unk>  testing can help confirm or rule out<unk> es. Correct diagnosis, counseling, and avoidance advice based on valid<unk>  test results reduces the incidence of symptoms and need for medications, and improves quality of life. To assess the presence of<unk> n-specific IgE antibodies, two different methods can be used: a skin prick test, or an<unk>  blood test. Both methods are recommended, and they have similar diagnostic value. Skin prick tests and blood tests are equally cost-effective, and health economic evidence shows that both tests were cost-effective compared with no test. Also, early and more accurate diagnoses save cost due to reduced consultations, referrals to secondary care, misdiagnosis, and emergency admissions.<unk>  undergoes dynamic changes over time. Regular<unk>  testing of relevant<unk> ns provides information on if and how patient management can be changed, in order to improve health and quality of life. Annual testing is often the practice for determining whether<unk>  to milk, egg, soy, and wheat have been outgrown, and the testing interval is extended to 2–3 years for<unk>  to peanut, tree nuts, fish, and crustacean shellfish. Results of follow-up testing can guide decision-making regarding whether and when it is safe to introduce or re-introduce<unk> nic food into the diet. Skin prick testing Skin testing on arm Skin testing on back Skin testing is also known as "puncture testing" and "prick testing" due to the series of tiny punctures or pricks made into the patient's skin. Small amounts of suspected<unk> ns and/or their extracts (e.g., pollen, grass, mite proteins, peanut extract) are introduced to sites on the skin marked with pen or dye (the ink/dye should be carefully selected, lest it cause an<unk> c response itself). A small plastic or metal device is used to puncture or prick the skin. Sometimes, the<unk> ns are injected "intradermally" into the patient's skin, with a needle and syringe. Common areas for testing include the inside forearm and the back. If the patient is<unk> c to the substance, then a visible inflammatory reaction will usually occur within 30 minutes. This response will range from slight reddening of the skin to a full-blown hive (called "wheal and flare") in more sensitive patients similar to a mosquito bite. Interpretation of the results of the skin prick test is normally done by<unk> sts on a scale of severity, with +/− meaning borderline reactivity, and 4+ being a large reaction. Increasingly,<unk> sts are measuring and recording the diameter of the wheal and flare reaction. Interpretation by well-trained<unk> sts is often guided by relevant literature. Some patients may believe they have determined their own<unk> c sensitivity from observation, but a skin test has been shown to be much better than patient observation to detect<unk> . If a serious life-threatening anaphylactic reaction has brought a patient in for evaluation, some<unk> sts will prefer an initial blood test prior to performing the skin prick test. Skin tests may not be an option if the patient has widespread skin disease, or has taken antihistamines in the last several days. Patch testing Patch test Patch testing is a method used to determine if a specific substance causes<unk> c inflammation of the skin. It tests for delayed reactions. It is used to help ascertain the cause of skin contact<unk> , or contact dermatitis. Adhesive patches, usually treated with a number of common<unk> c chemicals or skin sensitizers, are applied to the back. The skin is then examined for possible local reactions at least twice, usually at 48 hours after application of the patch, and again two or three days later. Blood testing An<unk>  blood test is quick and simple, and can be ordered by a licensed health care provider (e.g., an<unk>  specialist) or general practitioner. Unlike skin-prick testing, a blood test can be performed irrespective of age, skin condition, medication, symptom, disease activity, and pregnancy. Adults and children of any age can get an<unk>  blood test. For babies and very young children, a single needle stick for<unk>  blood testing is often more gentle than several skin pricks. An<unk>  blood test is available through most laboratories. A sample of the patient's blood is sent to a laboratory for analysis, and the results are sent back a few days later. Multiple<unk> ns can be detected with a single blood sample.<unk>  blood tests are very safe, since the person is not exposed to any<unk> ns during the testing procedure. The test measures the concentration of specific IgE antibodies in the blood. Quantitative IgE test results increase the possibility of ranking how different substances may affect symptoms. A rule of thumb is that the higher the IgE antibody value, the greater the likelihood of symptoms.<unk> ns found at low levels that today do not result in symptoms can not help predict future symptom development. The quantitative<unk>  blood result can help determine what a patient is<unk> c to, help predict and follow the disease development, estimate the risk of a severe reaction, and explain cross-reactivity. A low total IgE level is not adequate to rule out sensitization to commonly inhaled<unk> ns. Statistical methods, such as ROC curves, predictive value calculations, and likelihood ratios have been used to examine the relationship of various testing methods to each other. These methods have shown that patients with a high total IgE have a high probability of<unk> c sensitization, but further investigation with<unk>  tests for specific IgE antibodies for a carefully chosen of<unk> ns is often warranted. Laboratory methods to measure specific IgE antibodies for<unk>  testing include enzyme-linked immunosorbent assay (ELISA, or EIA), radioallergosorbent test (RAST) and fluorescent enzyme immunoassay (FEIA). Other testing Challenge testing: Challenge testing is when small amounts of a suspected<unk> n are introduced to the body orally, through inhalation, or via other routes. Except for testing food and medication<unk> es, challenges are rarely performed. When this type of testing is chosen, it must be closely supervised by an<unk> st. Elimination/challenge tests: This testing method is used most often with foods or medicines. A patient with a suspected<unk> n is instructed to modify his diet to totally avoid that<unk> n for a set time. If the patient experiences significant improvement, he may then be "challenged" by reintroducing the<unk> n, to see if symptoms are reproduced. Unreliable tests: There are other types of<unk>  testing methods that are unreliable, including applied kinesiology<unk>  testing through muscle relaxation), cytotoxicity testing, urine autoinjection, skin titration (Rinkel method), and provocative and neutralization (subcutaneous) testing or sublingual provocation. Differential diagnosis Before a diagnosis of<unk> c disease can be confirmed, other possible causes of the presenting symptoms should be considered. Vasomotor rhinitis, for example, is one of many illnesses that share symptoms with<unk> c rhinitis, underscoring the need for professional differential diagnosis. Once a diagnosis of asthma, rhinitis, anaphylaxis, or other<unk> c disease has been made, there are several methods for discovering the causative agent of that<unk> .
Allergy
Foodborne illness
Hypersensitivity
Food intolerance
Alloimmunity
Bronchiolitis
Pseudoallergy
Scombroid food poisoning