Evidence check: tTG IgA in the context of fatigue

The query concerns the biomarker tTG IgA (tissue transglutaminase IgA antibodies) in the context of fatigue. The provided knowledge base contains no information about tTG IgA, celiac disease, or its symptoms. From general medical knowledge, tTG IgA is a well-established serological marker for celiac disease (gluten-sensitive enteropathy). Fatigue is one of the most common extraintestinal symptoms of undiagnosed celiac disease, and guidelines recommend celiac serology (tTG IgA plus total IgA) in unexplained fatigue. The evidence for this link is strong in the medical literature (numerous cohort studies, meta-analyses). However, the present context cannot support this claim because it lacks any relevant studies or sources. Therefore, the evidence must be rated as 'unclear' here – not because the test is ineffective, but because the provided documents offer no relevant information. A negative tTG IgA largely rules out celiac disease (high negative predictive value); a positive result requires duodenal biopsy for confirmation. Fatigue has many causes; a standalone tTG IgA test without clinical context is insufficient.