Total IgE (Blood)

Diagnostic Use

IgE is responsible for the clinical signs and symptoms of an immediate-type allergic reaction. In allergic diseases, the total IgE concentration in serum is generally correlated with the intensity of allergen exposure and the severity of the allergic symptoms. In bronchial asthma, concentrations up to seven times the upper limit of the reference range are found (2). Total IgE concentrations of the same magnitude are found in atopic dermatitis (3). The determination of Total IgE can therefore be of aid in the diagnosis of allergic diseases. Serum Total IgE concentrations have special significance, particularly in children, in screening patients with allergic symptoms. One finds elevated serum total IgE concentrations in parasitic diseases (4). Values up to about 15 times the upper limit of the reference range can be reached. Extremely high concentrations occur in rare cases of IgE myeloma. Very low total IgE levels occur in nearly all forms of hypogammaglobinemia. In individual cases, total IgE concentrations may fall below the detection limit.

Specific IgE is a test which measures the concentration of circulating allergen specific IgE in Human serum or plasma.

Elevated total IgE levels can be helpful in distinguishing diseases of atopic genesis from non-atopic disease. Total IgE determination results should always be evaluated in the light of clinical and other laboratory results because low total IgE levels do not necessarily show the absence of allergies and high total IgE levels are not confined to allergic diseases; specific investigations to demonstrate allergy may be required.

In patients suffering from extrinsic asthma, hay fever or atopic eczema, symptoms develop immediately after exposure to specific allergens. This immediate (atopic or anaphylactic) type of allergy is a function of a special type of serum antibodies belonging to the IgE class of immunoglobulins.

High levels of serum IgE (>100 kIU/L) tend to be found more commonly in atopic patients, although lower levels do not exclude atopic illnesses. Markedly elevated levels are associated with allergic bronchopulmonary aspergillosis, parasitic infestation and hyper-IgE syndrome.

The measuring range of this assay is 2-5000Ku/L. In most cases estimating IgE level beyond 5000 does not influence clinical management and is not required. However, if the patient has a rare condition (eg Hyper IgE syndrome or IgE myeloma) total IgE levels beyond 5000 may be quantified.

Reference Intervals

<100 kIU/L