Why We Can't Rely on Blood Testing to Diagnose Allergies... & How it Delays Future Prevention/Interv

Have you ever  been referred to a specialist, when you were hoping to simply get your diagnosis from your family practitioner, a one stop shop type deal? While the idea of a quick diagnosis seems pleasant, in some cases it could be life threatening. 

A pediatric patient arrived at her pediatrician after developing hives after a meal. Her mother was unsure of what may have caused the reaction, as there were multiple foods eaten at the same time. The pediatrician offered to do an allergy test, IgE blood serum (RAST) her blood was drawn in their office that day, and they were sent home and advised to avoid foods suspected, as well as go straight to the er if there are any reactions indicating anaphylaxis. They would call in 7-14 days with her test results telling her what she may be allergic to. 

In this situation, the allergist should have been consulted, as anaphylaxis can be life threatening without any warning. The first reaction should be taken seriously, and results should be expected the same day, in order for the patient to avoid the life threatening food(s.)

There are several important differences in the two forms of testing. Blood testing is nice, because it is minimally invasive, and less time in office. However, the wait time for results can be fatal, as well as less accurate. The advantage of blood testing is that medicines don't have to be discontinued before the test, as well as benefiting  those with skin disorder (eczema, urticaria, dermatographism) where skin testing could likely show false positives and further delay intervention.

While generalists are a great starting place to point your towards the right specialists, always remember that the difference is the amount of experience in one specific field, over years. When you visit an allergist, your office visit is specifically dedicated to assessing, diagnosing, and treating allergies in the quickest way possible.

Time and accuracey are both critical to the diagnosis and treatment of allergic reactions/anaphylaxis.