A simple blood test can predict who can have severe allergic reactions to peanuts and seafood researchers from Mount Sinai Hospital have reported. Do you hate seafood and peanuts? You might want to take this blood test to detect whether you have an allergy to them. Researchers from Mount Sinai Hospital have reported that To detect food allergies physicians typically use skin prick tests or blood tests that measure levels of allergen-specific IgE (sIgE) a protein made by the immune system. Read about how self-medication for allergies can be dangerous. However these tests cannot predict the severity of allergic reactions.