Coeliac blood test.

[Dilbertian]

Oh joy. I know what eating wheat does to me. But it has to be done. How much do I need to eat every day?

I had this test about 15y ago. It was negative then. Could it have been a false negative? Or could it be that the disease wasn't sufficiently active then for the antibodies to be detectable?

Iirc it’s the equivalent of two slices of bread every day, at different meals, for 6 weeks.
You can have false negative blood tests.

https://www.coeliac.org.uk/information-and-support/coeliac-disease/getting-diagnosed/blood-tests-and-biospy/#:~:text=Negative%20blood%20test%20results&text=If%20you%20weren't%20eating,been%20tested%20for%20IgA%20deficiency.