Mine showed I was allergic to soy but the histamine and salt water didn't react.

We had a hunch I was allergic to soy prior to the test, so the test resulted in the doctor saying we can either do the test again or assume I'm allergic to soy and change my diet. The plan of attack wouldn't really change, just asked if I wanted confirmation.

Also, they can't charge me for the misfired test apparently which was nice.