Allergy specific tests are performed to identify sensitisation to one or more allergens that might be causing symptoms. Allergic patients are sensitised to allergens. The organism of these patients mounts an immune response that becomes harmful for them, while non-allergic persons can tolerate contact with allergens with no symptoms. The allergens responsible for that immune response, mediated by antibodies or cells, are identified with allergy specific tests.
Immunodeficiency tests evaluate the capacity of the organism to fight infections. The various mechanisms involved in defense against microbes are impaired in immunodeficient patients. Immunodeficiency tests try to identify the specific mechanism that is affected.
Functional tests are not allergy specific, but measure the impact of the disease in the affected organs. They assess the degree of inflammation or obstruction in the respiratory system. They are used for diagnosis when symptoms are not clear, and to monitor changes in the course of the diseases.
Other tests are performed to rule out other conditions that mimic allergic diseases or complicate their course.