Vitamin D deficiency/Coeliac disease

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My teenage ds has recently been tested for coeliac disease by a blood test, this is the third time and it was negative again.
He was eating gluten at the time, how accurate is the blood test?
My son is extremely thin and has constant bowel issues, he did have a scan last year to rule out chrohns disease and apart from slight thickening the US was passed as normal.
We have been back to the doctor again and he has been diagnosed with extremely low Vitamin D levels, this was also an issue last year so this is the second time in a year he has needed to be prescribed high dose Vitamin D.
There is a family history of Coeliac disease, his older brother, diagnosed as a toddler, even though the blood tests have been negative could CD still be a possibility?

The blood tests are considered highly reliable. No antibodies, no allergy. Eating gluten would have no effect on the serology testing.

Celiac disease is really quite rare and usually asymptomatic. For some reason patients often become absolutely convinced that they have it (or someone else has it) despite all evidence to the contrary.

If you are on Facebook, join the children with coeliac disease group and ask the same question there. I know there is a gene blood test they can do, but don't know in what circumstances they do it. Both me and dd have coeliac disease, but both diagnosed though positive TTG and biopsy.

His brother who was very symptomatic and was an inpatient for 3 weeks because of the severity of it when he was first diagnosed.
Doctor did seem fairly confident he didn’t have it, just wondering where to go from here now.

mummy I will request to join the FB group.
My eldest son was diagnosed via biopsy as at that time there was no blood test.
Sorry, what is TTG?

How much gluten is he/was he eating? I've been told you have to eat it three times a day for at least 3 months (or is it 6?!) I've got it and two of my children have tested negatively.

Has he had a gastroscopy to look inside his stomach and examine his Villi?

My teenage DS was diagnosed that way & then confirmed with the blood test after.

And Coeliac disease is NOT quite rare - it's 1 in 100 people, rising to 1 in 10 if a close family member has it, so there's definitely a good chance your DS has it OP.

Are you a member of Coeliac UK, they give lots of helpful advice?

MissConductUS coeliac disease is not an allergy. it's an autoimmune disease.

I was tested first by blood test and then by gastroscopy; the blood test is apparently 99.9% accurate or something like that. This was over a decade ago, though!

Wow, what a lot of contradictory advice on here! Sorry, op. Miss- are you in the USA?

TTG is the blood test (Tissue transglutaminase antibody (tTG), IgA class — the primarytest ordered to screen for celiac disease - from Google!!).

I find the fb group really helpful plus also get some great tips on new gf foods available. I'm sure I've read cases on there of negative bloods and follow up gene test.

Actually Brutus DS was diagnosed the wrong way round - he had no typical coeliac symptoms & coeliac disease wasn't suspected initially.

So they did the gastroscopy to have a look, then he had the blood test.

Sorry if I've confused anyone.

I haven't eaten gluten for years (I had worked out it caused me problems), I don't show up on any tests (bloods, endoscopy), yet I am coeliac too. I have 2 other illnesses which are strongly related to coeliac disease - an inflammatory bowel disease (lymphocytic colitis) and exocrine pancreatic insufficiency - and so that's what the consultant has determined. So it really isn't as straightforward as showing up on tests.

My son had the camera up first and bloods later as they didn't think it was (it was)

you Need an endoscopy to look at the villi. He needs to be fully eating a lot of gluten heavy foods for a while before the biopsy.

You don't necessarily need to eat lots of gluten for it to show up in the blood tests. I've been as gluten free as I can reasonably be for about 2 years but the blood tests still show up coeliac antibodies because I use the same butter, jam etc, as the rest of the family, and I store my GF bread (wrapped up) in the same cupboard as the regular bread, so occasionally I get some crumbs / cross contamination. I'd be pretty confident if he's had 3 negative blood tests that he doesn't have it.
FWIW most people in the UK are Vit D deficient, because of the angle of the sun's rays at our latitude between October and April. We can't absorb the Vit D at that refraction (or something... I didn't really understand when the GP was explaining it to me!)

Vitamin D deficiency can cause all sorts of odd symptoms. That’s what the paediatrician we saw recently said.

DS2 was referred for migraines and joint pains. I have an autoimmune arthritis condition, so I was more worried it might be that. But the paediatrician thought it could be vitamin d deficiency or coeliac.

The coeliac test was very strongly positive so he’s recently had another one (plus a test for a particular genetic marker). Apparently he shouldn’t need a biopsy if the results of the tTG are as high as last time and he has one of the associated gene markers. We’re waiting to see the paediatrician gastroenterologist at the moment.

My friends who are doctors said that the tests are really pretty specific and reliable. But, if the test is going to be wrong, then a false negative is much more likely than a false positive (particularly at the level
DS2 has).