Total IgE

Function

Immunoglobulin E (IgE) is a class of antibodies produced by the immune system that plays a pivotal role in Type I hypersensitivity reactions (allergic reactions) and the defense against parasitic infections. While IgE is typically present in the blood in very low concentrations, its production increases significantly when the body overreacts to environmental allergens or encounters specific pathogens.

Why it is Ordered

The Total IgE test is ordered as a preliminary screen for allergic diseases. It helps clinicians differentiate between allergic and non-allergic respiratory conditions (such as allergic vs. vasomotor rhinitis). It is also used in the diagnosis of Allergic Bronchopulmonary Aspergillosis (ABPA) and to screen for parasitic infestations. In some cases, it helps determine if a patient is a candidate for certain biologic therapies (like Omalizumab) for severe asthma.

Associated Conditions

• Atopic Diseases: Including asthma, hay fever (allergic rhinitis), and atopic dermatitis (eczema).
• Parasitic Infections: Specifically helminthic (worm) infestations like ascariasis or hookworm.
• Hyper-IgE Syndrome (Job's Syndrome): A rare genetic primary immunodeficiency.
• Multiple Myeloma: Rarely, an IgE-secreting myeloma can occur.

While a high Total IgE suggests an allergic predisposition (atopy), it does not identify the specific allergen responsible; further 'Specific IgE' or skin prick testing is required for targeted diagnosis.