Allergy testing: scratch test/rasp/blood whats what?!

[aiccerb]

We are currently seeing a ped for our middle child (for behavoir/sensory issues) and the conversation of allergies keeps coming up. He perpetually has skin rashes/exzema and chronic diahreah (sp?). We removed peanuts/legumes from his diet and the diahreah has cleared up for months now, but the exzema is still an on going prob.

At our last appointment the ped said he wants to do a blood draw to figure out what's happening. This seemed a little much to me as a starting place and I asked to hold off till next appt (so I can check in with you mamas) to see what course of action you would reccomend having been there/done that.

Whats the difference between a scratch test/rasp/blood draw etc? Which are more reliable, painful etc etc. I'd love to hear any ideas or suggestions.

[wendy1221]

The most reliable method is an elmination diet. As for RAST (blood test) and the SPT (skin test), neither is very accurate in kids under 4. For some people 1 works and the other doesn't, and for some neither works, and for others both are accurate. But you never know which category you're in. Elmination diets are the only way to know for sure. I would say the blood draw is harder than the SPT.

[cat19]

For both my sons, skin prick tests very very useful and accurate, at ages five months old and two and a half, respectively. It depends on the kid. And for my kids, blood tests were the easiest; quick pinch and over fairly fast. Skin tests take longer and if your kid's skin reacts they can get quite itchy. Rast tests are blood tests.

Skin tests are more prone to false positives and blood tests to false negatives, assuming your kid has allergies that are IgE-mediated to begin with.

I'd start requesting a referral to a pediatric allergist and to a dermatologist (one familiar with kids' skin and allergic eczema) while waiting for the appointments, I'd go with a detailed food/reaction diary and an elim diet to try to get your kid's skin to baseline (no eczema, no other reactions) by eliminating your prime suspects--dairy, soy, wheat, eggs, fish, shellfish, treenuts or some subset of those based on your sense of your child's diet, and some people might suggest corn and/or sesame as well.

I'd also expect the dermatologist and the allergist could give you help and advice in figuring out possible culprits and in basic eczema skin care--humidity, wet wraps, Eucerin cream, vaseline, some use of hydrocortisone, possibly steroid use if the eczema is quite bad, possibly a daily antihistamine if that seems indicated. I'd check into your detergent, wash bedding very frequently in HOT water, and so on.

I would not go with tests ordered by your ped (though I agreew with him/her that allergies seem a possibile cause worth pursuing) as you really need a very experienced allergist to interpret tests and the child's history together, and a good pediatric allergist knows much more clearly how to track down possible allergens. Most peds just aren't going to have the level of familiarity and expertise to interpret a skin test or to know which allergens are most likely in your child's situation.