Can You Get A False Negative If Already gluten-free?

[ruhbehka]

DS is 3.5 and gets a characteristic itchy rash when exposed to gluten, along with his intestinal symptoms. He has never made it past a few days on a gluten challenge (we're seeking a definitive celiac diagnosis) because his bowels get so terrible that the doctor calls it off (black and tarry one time; nonstop poop + gobs and gobs of mucus that lasted weeks after, another time).

But I read that you can get a positive skin biopsy for DH, if you have it.

DS had a recent exposure to gluten (haven't figured out the source yet) and starting yesterday he had the nonstop pooping, exhaustion, gas, belly aches. This morning his "gluten rash" appeared in the usual spots (sides of his under-arms, middle of his belly) and he's already itching like crazy. In the past, a friend with DH mentioned that it looks EXACTLY like his DH presents.

We are wondering if we could get him a skin biopsy that would give an accurate result, since he has been on a gluten-free diet for over 2 years (other than 3 exposures or challenges). If the outbreak is triggered by a gluten exposure, would the biopsy show up positive even though your bloodwork wouldn't?

Need to figure out if we should ask the ped for a referral first thing tomorrow!

[GFinDC]

That's my understanding, that DH can be biopsied near the lesion not in. DH only happen with celiac, so if they test it and he has DH then yes he has celiac.

[ravenwoodglass]

He just needs an active lesion which it sounds like he has. Just make sure the Derm knows to biopsy next to the lesions and that he is looking for DH. A diagnosis of DH is a diagnosis of celiac. I hope your little guy feels better soon.

[ChemistMama]

I was gluten-free for several months and my skin biopsies came back negative. I've read several places that it takes at least a year sometimes to get all of the gluten antibodies out of your skin, so at two years gluten-free I wouldn't be surprised if his biopsy came back negative. Since he's had gluten, I would try the iodine patch test near one of his lesions (soak a bandaid in topical iodine solution, the kind you buy to put on cuts. let it stay on his skin near a lesion for 12 hours, if he can stand it. If it gets red and irritated and itchy he has DH. After 12 hours, wait another 24 to see if a blister forms at the site of the bandaid.)

My dermatologist contacted some celiac specialists and said I'd have to be on gluten for about 2 weeks to get a positive biopsy. I tried a challenge but couldn't handle it, it was too painful and itchy!

Back before skin biopsies, a positive diagnosis of DH was made if the person responded to dapsone. After 24-36 hours, if you have DH, the lesions will subside, but dapsone can be a nasty drug, too.

Some tips to make him feel better: try Sarna sensitive lotion (the kind that doesn't smell like menthol), and make sure he doesn't have any Advil or iodine-containing foods like vitamins or shellfish or seaweed until his break outs subside. Iodine can catalyze a reaction.

Good luck!