How accurate are blood tests?

[Newton2]

I originally was admitted to hospital 4 times in one month, stayed in total for over two weeks in total. Had a serious bout of gastroenteritis. I had administered over 22 different drips in that period.

On the last occasion I was told my blood tests showed coeliac Disease. I have been so ill I declined the endoscopy. How accurate alone are the blood tests? I lost two stone in one month, seriously unwell. I am undef the gastro team and a dietician. I have been following gf diet for two months and am improving. Very slowly. I also had peritonitis of my intestines. I had no signs of coeliac before this. What do you all think? Thanks for any feed back

[Suit]

I believe that the ttg-IgA has a sensitivity of 98% and a specificity of 95%

Meaning that 98% of positive tests are true, 1 out of 50 might not have transglutaminase autoantibodies with an actual coeliac disease.

And 95% of negative tests are true, meaning that 1 out of 20 with autoantibodies don't have celiac disease.

If you are one of those 1/20 who doesn't actually have coeliacs disease, then you'd just be eating gluten free for no medical purpose.

But since you are improving, then you probably are one of those 49 true positives.

If you want to know for sure, then there still might be time to check your vili before it's completely healed.

[Hidden in reply to Suit]

That's good information. To clarify, what you are saying on the 1-20 is that for every 20 people who show a negative coeliac test, one of those will actually have coeliac?

[Suit in reply to Hidden]

Sorry, I mixed the words up.

1 in 20 are falsely positive on ttg-IgA.

1 in 50 are falsely negative.

Sensitivity measures how accurate the test is to identify those who actually have celiac. If 98% of those with celiac have a positive testresult, then 2% will have a false negative test.

If 95% of the healthy population have a negative test, then 5% will have a positive test despite being "healthy". This is probably in the Lower range.

But I think people with diabetes and a couple of other autoimmune diseases can test positive, without having celiac. Hence falsely positive.

[Hidden in reply to Suit]

Thank you!