The full answer
The tTG-IgA test is the standard first test
The most common celiac disease blood test measures tissue transglutaminase IgA antibodies (tTG-IgA), which the immune system produces in response to gluten in most people with the condition. Total IgA is often tested alongside it, since a small number of people have an IgA deficiency that would make the main test unreliable on its own — in that case, an IgG-based version is used instead.
What happens after a positive result
A positive tTG-IgA result strongly suggests celiac disease but is typically followed by an endoscopy and biopsy to confirm the diagnosis before starting lifelong dietary changes.
Important context
Individual symptoms, reactions, medical histories, food products, and local labeling rules can vary. Community experiences are not medical evidence.
For personal medical decisions, diagnosis, testing, or treatment, consult a qualified healthcare professional.