Testing 1, 2, 3, or How I Became a Meat-Eating Vegan with Celiac Sprue

"We're pretty sure he's allergic to milk," I told Dr. P, Pete's allergist.

It was skin prick testing day. As per doctor's orders, we had ceased using hydrocortizone for the three days preceding this first appointment, and we omitted Pete's daily lotion schmear following his morning bath. Any medications with antihistamine-like actions (these include those taken internally and applied externally) can skew the testing results by preventing a reaction. The slickery nature of moisturizers can cause the allergen extracts to run into one another.

While skin prick testing is most commonly done on the forearm, children younger than two years are generally tested on their backs to prevent them from itching and thereby smearing the extracts. The nurse first wiped Petey's back with alcohol and then pricked him with tiny lancets that had been first dipped in specific allergen extracts. The allergen is thus introduced under the surface of the skin where an allergic reaction is triggered. The prick itself is not painful, the only discomfort is the itchiness from the reaction.

Keeping in mind that I majored in English, here's my understanding of the process by which an allergic reaction occurs. The immune system produces many immunoglobulins (also known as antibodies), one of which is immunoglobulin E, or IgE. It is the primary player in allergic reactions. IgE antibodies are incredibly specific and respond only to their own allergen. For instance, an IgE antibody for peanuts will react only against peanuts and not hazelnuts or Brazil nuts. When IgE antibodies recognize the allergen against which they are programmed, they trigger the body's mast cells to release defensive chemicals (including histamine) into the body's tissues. These chemicals cause allergic reactions.

After 15 minutes, the nurse returned and checked for wheals (little lumps like mosquito bites) on Pete's back. A milk allergy was confirmed and allergies to wheat, egg whites, and peanuts discovered. While skin-prick testing can determine one's allergens, it is unable to indicate the degree to which one is allergic. That's where RAST blood testing enters the picture. It measures the amount of IgE directed against specific allergens.

Dr. P's advice at this point was to continue breastfeeding for as long as possible and to delay the introduction of solid foods. This, however, would require that I eliminate all of Pete's allergenic foods from my own diet until he is weaned. Sign me up; I'd do anything for this kid.