What to watch with tTG IgA and weight loss?

tTG-IgA (tissue transglutaminase IgA) is the primary serological marker for celiac disease. Unexplained weight loss should prompt celiac screening, especially if accompanied by diarrhea, fatigue, or iron deficiency. A positive tTG-IgA requires confirmatory duodenal biopsy. Important: Testing must be done on a gluten-containing diet to avoid false negatives. In IgA deficiency, the test can be falsely negative – then IgG-based tests (e.g., tTG-IgG, DGP-IgG) are indicated. After diagnosis and gluten-free diet, tTG-IgA typically normalizes within 6–12 months, with weight stabilization. Caveat: Weight loss may also stem from thyroid disorders, diabetes, or malignancy. Evidence for the tTG-IgA–celiac link is strong (human-strong).