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Allergy skin test

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Also listed as: WAS
Related terms
Background
Author information
Bibliography
Who should not be tested
Preparing for the test
How it is performed
Results
Risks

Related Terms
  • Antibodies, auto recessive, B-cells, bone marrow, bone marrow transplant, CBC, genetic disorder, immune system, immunodeficiency, inherited disorder, inherited immunodeficiency, leukocytes, leukemia, lymphoma, lymphocytes, malignancy, platelets, pneumonia, red blood cells, T-cells, thrombocytes, thrombocytopenia, tumor, WASP, white blood cells, Wiskott Aldrich syndrome, Wiskott-Aldrich syndrome protein, X-linked.

Background
  • Wiskott-Aldrich syndrome (WAS) is an inherited, immunodeficiency disorder that occurs almost exclusively in males. The recessive genetic disorder is caused by a mutation in the WAS (Wiskott-Aldrich syndrome) gene, which is an X-linked trait. The gene mutation leads to abnormalities in B- and T-lymphocytes (white blood cells), as well as blood platelet cells. In a healthy individual, the T-cells provide protection against viral and fungal infection, the B cells produce antibodies, and platelets are responsible for blood clotting to prevent blood loss after a blood vessel injury.
  • Individuals diagnosed with WAS suffer from recurrent infections, eczema and thrombocytopenia (low levels of platelets).
  • Before 1935, patients only lived an average of eight months. Today, patients usually live an average of eight years, according to a recent case study. The cause of death is usually attributed to extensive blood loss. However, cancer (especially leukemia) is common and often fatal among WAS patients.
  • The only possible cure for WAS is a bone marrow transplant. However, if a patient's family member is not a possible match for a bone marrow donation, patients may have to wait years for a potential donor. Other aggressive treatments may also increase a patient's life expectancy. For instance, one study found that patients who underwent splenectomy (removal of the spleen) lived to be more than 25 years old. The spleen may harbor too many platelets, and cause a decrease in the number of platelets in circulation. Antibiotics, antivirals, antifungals, chemotherapeutic agents, immunoglobulins and corticosteroids have also been used to relieve symptoms and treat infections and cancer associated with WAS.
  • Researchers estimate that about four people per one million live male births develop the disease in the United States.
  • The syndrome is named after Dr. Robert Anderson Aldrich, an American pediatrician who described the disease in a family of Dutch-Americans in 1954, and Dr Alfred Wiskott, a German pediatrician who discovered the syndrome in 1937. Wiskott described three brothers with a similar disease, whose sisters were unaffected.

Author information
  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography
  1. Binder V, Albert MH, Kabus M, et al. The genotype of the original Wiskott phenotype. N Engl J Med. 2006 Oct 26;355(17):1790-3.
  2. Jin Y, Mazza C, Christie JR, et al. Mutations of the Wiskott-Aldrich Syndrome Protein (WASP): hotspots, effect on transcription, and translation and phenotype/genotype correlation. Blood. 2004 Dec 15;104(13):4010-9. Epub 2004 Jul 29.
  3. Natural Standard: The Authority on Integrative Medicine. .
  4. St. Jude Children's Research Hospital. Inherited Immunodeficiencies: Wiskott-Aldrich Syndrome (WAS). .
  5. U.S. Immune Deficiency Foundation. The Wiskott Aldrich Syndrome. .

Who should not be tested
  • Certain medications, including antihistamines like fexofenadine (Allegra®), diphenhydramine (like Benadryl®) and cetirizine (Zyrtec®), antidepressants like amitriptyline and doxepin (Sinequan®) and some heartburn medications like cimetidine (Tagamet®) and ranitidine (Zantac®), may interfere with test results. A qualified healthcare provider will determine if it is better to continue taking the medications or discontinue the medications temporarily, until the test is performed.
  • Patients who have severe skin diseases (like eczema or psoriasis) that are present on large areas of skin on the arms or back may be discouraged from taking the test. This is because the test is typically performed on the arms and back, and there may not be enough unaffected skin to perform a conclusive test.
  • Individuals who are extremely sensitive to suspected allergens might be advised not to undergo the test. Some patients may be so sensitive to certain substances that even trace amounts could trigger a severe allergic reaction called anaphylaxis.

Preparing for the test
  • Before a skin test is performed, a qualified healthcare provider will ask questions about the patient's medical history, including any and all allergic symptoms that occur.
  • A qualified healthcare provider will perform a physical examination to determine if there is an underlying medical problem triggering the reactions.
  • In some cases, a medical history and physical exam may provide enough information for the healthcare provider to diagnose and treat the patient. In such cases, a skin test may not be needed. However, if the cause of the symptoms remains unknown, a skin test may be recommended.
  • Before a skin test is scheduled, a qualified healthcare provider will need a list of all the prescription and over-the-counter medications, as well as any herbs or supplements that the patient is taking. Some agents, including antihistamines like fexofenadine (Allegra®), cetirizine (Zyrtec®) and diphenhydramine (Benadryl®) may suppress allergic reactions, thus causing false negative skin test results. Others, including antidepressants like amitriptyline and doxepin (Sinequan®) and heartburn medications like cimetidine (Tagamet®) and ranitidine (Zantac®) may increase the patient's chance of experiencing a severe allergic reaction during the test.
  • Different medications can stay in the body for different lengths of times after they are discontinued. Therefore, a qualified healthcare provider may ask that the patient stop taking certain mediation for 10 days or more prior to the skin test. Patients should not stop taking any drugs, herbs or supplements without consulting their healthcare providers.

How it is performed
  • The allergen-specific IgE antibody test is an in vitro test, which means it is conducted outside of the body in a laboratory setting.
  • During the procedure, a sample of blood is taken from the patient.
  • The blood is then sent to a laboratory that performs specific IgE blood tests. Currently, more than 550 allergens are available for determinations.
  • An allergen-antigen complex is bound to an allergosorbent (paper disk) and the patient's blood is added. If the blood contains antibodies to the specific antigen, it will bind to the "tagged" immunoglobulins.
  • The patient will receive the test results in 7-14 days.

Results
  • If an allergen triggers an allergic reaction to a test, the patient will develop reddening, swelling or a raised, itchy red wheal (bump) that looks similar to a mosquito bite. The healthcare provider will measure the size of the wheal and record the results. The larger the wheal, the more severe the allergy is. The test site will be cleaned with rubbing alcohol to remove any remaining allergen extracts.
  • A positive skin test means the patient is allergic to a particular allergen. Larger wheals (bumps) usually indicate a higher degree of sensitivity. Wheals will resolve without treatment within a few days.
  • If there is no reddening, swelling or raised, itchy wheal at the test site, the results are negative, which suggest that the patient is not allergic to the particular allergen.
  • The accuracy of skin tests may vary. A false positive or false negative test result is possible. Other test results may be inconclusive. For instance, some patients may react positively to a substance during the test, but may not react to the allergen in everyday life.
  • Skin tests are most reliable when they are used to diagnose allergies caused by airborne allergens, including animal dander, dust mites and pollen. They are least reliable when they are used to diagnose allergies caused by contact.

Risks
  • There are no medical risks associated with the allergen-specific IgE antibody test. Slight bruising may occur at the site where blood was taken.
  • Unlike skin tests, there is no risk of a serious allergic reaction occurring during the antibody test because the patient's body is not exposed to the allergen.

Copyright © 2011 Natural Standard (www.naturalstandard.com)


The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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