Allergy testing can help confirm or rule out
allergies
Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic dermat ...
and consequently reduce adverse reactions and limit unnecessary avoidance and medications.
[Boyce, J ''et al''., "Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of NIAID-Sponsored Expert Panel", ''J Allergy Clin Immunol'' 2010; 126: S1–S58.][National Institute for Health and Care Excellence]
"Diagnosis and assessment of food allergy in children and young people in primary care and community settings"
2011. Retrieved 26 December 2019.
Correct allergy diagnosis, counseling and avoidance advice based on valid allergy test results is of utmost importance and can help reduce the incidence of symptoms, need for medications and improve quality of life.
[ A healthcare provider can use the test results to identify the specific allergic triggers that may be contributing to the symptoms. Using this information, along with a physical examination and case history, the doctor can diagnose the cause of the symptoms and tailor treatments that will help the patient feel better. A negative result can help the doctor rule out allergies in order to consider other possibilities. Ruling out allergies is as important as confirming them to limit unnecessary avoidance, worry and negative social impact.
]
Types of tests
NIH
The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late ...
guidelines for the diagnosis and management of food allergy and the diagnosis and management of asthma
Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, co ...
recommend either allergy blood testing or skin prick testing to reliably determine allergic sensitization.[
]
Blood test
For an allergy blood test, a sample of the patient's blood is sent to a laboratory for analysis. Allergy blood tests measure the presence of IgE antibodies to specific foods, pollens, mites, animals, insects and other environmental factors. (IgE, short for "immunoglobulin E", is the antibody that triggers food allergy symptoms.) The doctor looks at the test results to help determine if the patient has allergies. Allergy blood tests are not affected by antihistamine use and can be performed for people with extensive rashes that prevent using skin prick tests. For babies and young children, a single needle stick for allergy blood testing is often more gentle than several skin tests.
Skin allergy test
Skin allergy testing comprises a range of methods for medical diagnosis of allergies that attempts to provoke a small, controlled, allergic response.
Skin prick test
For a skin prick test
Skin allergy testing comprises a range of methods for medical diagnosis of allergies that attempts to provoke a small, controlled, allergic response.
Methods
A microscopic amount of an allergen is introduced to a patient's skin by various mean ...
, a patient is pricked with a series of needles that contain extracts of allergic triggers. The doctor looks for strong reactions like welts or red bumps to determine if the patient has allergies.[Asthma and Allergy Foundation of America]
"Skin Testing for Allergies"
25 June 2012. Retrieved January 2013. This method, although unpleasant for young children and people who dislike needle pricks, is beneficial because the person may discover an acute allergy with specially trained healthcare staff available to stop life-threatening allergic reactions such as an unexpected anaphylactic reaction
Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of use of emergency medication on site. It typically causes more than one of the follo ...
. It may also allow the person to be prescribed tools for intervention needed if anaphylaxis ever occurs again, such as a mobile epinephrine pen. Epinephrine acts quickly to vasoconstrict
Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vessel ...
, increasing blood flow to vital organs, and relaxing the smooth muscles in the airway, allowing the patient to breathe until emergency services arrive.
Patch test
Patch testing helps identify which substances may be causing a delayed-type allergic reaction in a patient and may identify allergens not identified by blood testing or skin prick testing. It is intended to produce a local allergic reaction on a small area of the patient's back, where the diluted chemicals were planted.
The chemicals included in the patch test kit are the offenders in approximately 85–90 percent of contact allergic eczema and include chemicals present in metals (e.g., nickel), rubber, leather, formaldehyde, lanolin, fragrance, toiletries, hair dyes, medicine, pharmaceutical items, food, drink, preservative, and other additives.
References
External links
Allergy blood testing information
from the AACC
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