What numbers are normal and what is elevated?
My sister also has problems with asthma and when we were researching about asthma and allergies we have found out that concentration of IgE is very low in the body when you don’t have any kind of problems with asthma or allergies.
Our doctor said that a normal IgE level is 4.2-595 U/mL or 0.05 percent of the IgG concentration and that high IgE levels are not only signs of asthma or allergy but they can also be a sign of infection, autoimmune disease or the presence of cancer.
Since you know that your daughter is suffering from asthma you can exclude other conditions.
Considering Xolair I know that one friend was using it and he was constantly complaining that it is more expensive than some other products he was using before. But if your doctor has recommended it maybe you should try.