As IgE is of importance in allergies, elevated IgE concentrations can be found in patients with allergic diseases such as hay fever, atopic bronchitis and dermatitis. Normal IgE values do not, however, mean that an allergic disease can be ruled out. For this reason the quantitative determination of serum IgE concentrations for clinical differentiation between atopic and nonatopic diseases is only useful in combination with other clinical findings.
Elevated serum IgE concentrations can also occur in non-allergic diseases, e.g. bronchopulmonary aspergillosis, Wiskott-Aldrich syndrome, hyper‑IgE syndrome, IgE myeloma, and parasitic infections.