Hello. Thank you for asking at HCM. Serum total IgE is a helpful/supportive investigation for some diseases, but it alone does not diagnose or rule out any condition. Serum Total IgE 2500 is considered a high value. The most common causes when it is elevated are allergic conditions like allergic rhinitis, asthma, atopic dermatitis, allergic respiratory aspergillosis, etc. However, it is not only associated with allergic causes. It can also be elevated in some intestinal worms infections, some rare immune disorders, etc. At this point I would suggest you to not to concentrate on IgE levels itself. It is important to know the cause of raised IgE levels. Appropriate management of the cause is the only important treatment. Regarding complications, they are mostly due to the diseases themselves. They are mostly not related to IgE levels. If your father is having allergies, I would suggest him to consult an Allergist-Immunologist who will advise him allergy testing and then suggest appropriate management of the condition. Hope this will be helpful to you. Wish your father the best of the health. Regards.