<\/span><\/h2>\nThe autologous serum skin test is a research test to autoimmune<\/span> urticaria<\/span>, which is a type of chronic<\/span> urticaria. It is carried out in specialized centers for some patients with chronic urticaria.<\/p>\nNormal immunoglobulin<\/span>-ME antibodies<\/span> (IgE) activates IgE receptors (FceRI) in mast cells<\/span> and basophils<\/span>. These cells release histamine<\/span>, an important mediator in allergic responses. Autoimmune urticaria is due to autoantibodies<\/span> that bind to these receptors or to the IgE antibodies themselves. This causes inappropriate activation of mast cells and basophils and the release of histamine.<\/p>\nAutologous serum skin tests detect circulating autoantibodies, indicating an autoimmune origin in some patients with chronic urticaria.<\/p>\n
<\/span>When are autologous serum skin tests done?<\/span><\/h2>\nInducible<\/span> Chronic urticaria can be detected when a certain stimulus causes scarring, such as cold air in cold urticaria or scratching the skin in dermographism.<\/p>\nSpontaneous or ordinary chronic urticaria may not have an obvious trigger. The autologous serum skin test can be a useful diagnostic tool because it confirms such cases due to autoimmunity<\/span>. If the test is negative, it is considered chronic spontaneous urticaria. idiopathic<\/span>, that is, it has no known cause.<\/p>\n\n<\/span>Chronic urticaria<\/span><\/h5>\n<\/section>\n\n\n
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Urticaria<\/p>\n
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Urticaria<\/p>\n
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Spontaneous urticaria<\/p>\n<\/p><\/div>\n<\/section>\n
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<\/span>Details of the procedure.<\/span><\/h2>\nThe patient should stop taking antihistamines 2\u20133 days before the autologous serum skin test, to ensure that their hives are active at the time of the test. Immunosuppressive agents can also be stopped for up to 3 months before the test.<\/p>\n
The test should not be done on an area of skin that has had cure<\/span> in the last 24 hours<\/p>\n\n- Two milliliters from the patient. venous<\/span> Blood is drawn, allowed to clot for 30 minutes, and then centrifuged to extract serum from the blood.<\/li>\n
- A small sample of serum is injected into the lower part of the patient's forearm.<\/li>\n
- Histamine is injected as positive control<\/span>and saline<\/span> Water is injected as a negative control.<\/li>\n
- There should be 5 cm gaps between each injection site.<\/li>\n
- The response is recorded after 30 minutes.<\/li>\n<\/ul>\n
A positive result occurs when the bump<\/span> formed where the serum is injected has a diameter that is at least 1.5 mm larger than the saline solution.<\/p>\n<\/span>What are the benefits of autologous serum skin tests?<\/span><\/h2>\nAutologous serum skin tests are relatively reliable, with a sensitivity of 70% and a specificity of 80%. It is inexpensive and easy to administer. <\/p>\n
<\/span>What are the disadvantages of autologous serum skin tests?<\/span><\/h2>\nAutologous serum skin tests should be performed by an experienced investigator; Poor technique can lead to false positive or false negative results.<\/p>\n
The test is not standardized, with several methods described in the literature and different criteria for a positive result.<\/p>\n
Positive results can occur in patients who do not have chronic urticaria, for example:<\/p>\n