Q. What is the indication of high Ig E level in the blood?
I am not sure what you exactly mean by indication of IgE level. I suppose you mean the reasons for it and perhaps the clinical manifestations of such a state.
Immunoglobulin E (IgE) is an antibody, which is specifically related to allergy and its levels go up in blood (and tissues) in allergic conditions. But measuring total IgE levels in blood is not very specific as this value can be raised in parasitic infections, immunologic disorders, some cancers (myeloma, Hodgkin's disease) and even smoking or consuming alcohol. A normal IgE level does not exclude significant allergic disease. The most common causes are allergic disorders (skin, respiratory tract, drugs), parasitic infestations, immunologic disorders, certain infections etc.
The IgE antibody is classically associated with what is called the Type I hypersensitivity reaction. In case of systemic reaction (called anaphylaxis) caused by drugs, toxins, venoms, blood products etc., the symptoms are severe and life threatening. These include severe breathing problem, circulatory collapse and swelling of body. A food allergy presents with vomiting, diarrhoea and skin reactions. Other allergic disorders like hay fever or asthma have symptoms specific to the organ involved.