Yesterday my daughter V went in for what has become a yearly ritual: her specific IgE blood test. She bravely went in after listening to the previous patient scream for 20 minutes. She yelped when she was stuck, but gritted it out while the nurse drew four vials of blood.
Four vials seems like a lot. My wife, who is a veterinarian, says she only takes one vial to test dogs for multiple allergens.
The process reminds me how little I know about medicine in practice.
IgE is a type of antibody, a Y-shaped molecule with sticky ends that recognizes allergens and triggers inflammation. Kaiser Permanente, our HMO, uses the ELISA test to measure IgE levels, instead of RAST, which has been abandoned since 2010 because it involves using radioactive material.
The first result came back as “IgE, QN 368 Standard range 0 - 75 U/mL”
"U" is for "unit." How many antibodies in a unit? I have no idea. The internet is no help here. 368 U/ml, from what I can tell, is her measure of total IgE, all the antibodies of this type she has circulating in her blood.
So that means V's IgE is five times the maximum normal limit. That’s typical for someone with atopy.
We’re still waiting for the specific results. I wouldn’t put it past Kaiser to waste at least one vial doing the wrong test, and then tell us we need to come in and give more blood.
Last year, among other things, V tested positive for IgE against milk, with 7.8 U/mL. I find it remarkable that her titer of antibodies to milk is 10% of the maximum number of antibodies that a “normal” person should have against everything.
V has eczema and mild asthma. Positive IgE tests are no guarantee of allergy, but we know she’s allergic to milk, since she vomits every time we give it to her. (Our son has no allergies and my wife and I have accidentally switched the kids’ glasses at lunch. Oops.)
She also has consistently tested positive for peanut and walnut allergy (and beef!), though there are as yet no incidents where she’s eaten some and had a reaction. We’re just trying to keep tabs on her allergies as she grows up, hoping, of course, that they will go away—but also fearing that she could develop a life-threatening allergy.