What to watch with tTG IgA and gut health?

tTG IgA (tissue transglutaminase IgA) is the primary screening marker for celiac disease, an autoimmune enteropathy triggered by gluten. Elevated levels indicate an immune response against gut tissue, but the test alone is not diagnostic. Key watchpoints: IgA deficiency (2–3% of celiac patients) can cause false negatives, so total IgA should always be measured. Elevated tTG IgA can also occur in other autoimmune conditions (e.g., Crohn's, autoimmune hepatitis) or infections. Gut health extends beyond celiac: tTG IgA does not assess microbiome diversity, intestinal permeability, or non-celiac gluten sensitivity. A positive result requires confirmation via duodenal biopsy (or in children, high titers plus HLA typing). Do not start a gluten-free diet before full diagnostic workup, as it lowers antibodies and may obscure histology. Consumer tests offer a screening hint but are not a substitute for clinical evaluation. Evidence: human-strong (clinical guidelines).