Tissue Transglutaminase IgG Antibody

Tissue transglutaminase antibody IgG is an IgG-class autoantibody targeting tissue transglutaminase, an enzyme in the intestinal lining. It’s tested to help diagnose celiac disease—particularly in people with IgA deficiency or inconclusive IgA results. Elevated tTG‑IgG suggests an immune reaction to gluten and intestinal damage; levels typically decline on a strict gluten-free diet and can be used to monitor response.

There is no single universal IgG level that definitively indicates celiac disease. IgG-based tests (deamidated gliadin peptide IgG or tTG‑IgG) are interpreted against the laboratory’s reference range; a value above the lab’s positive cutoff—commonly around 20 U/mL—raises suspicion, especially with IgA deficiency. Diagnosis requires confirmatory evaluation (duodenal biopsy and/or HLA typing) and clinical correlation.

A positive tissue transglutaminase (tTG) antibody test suggests likely celiac disease but isn’t definitive. Next steps include checking total IgA, confirmatory duodenal biopsy (or specialist assessment), or alternative IgG-based serology if IgA-deficient; HLA DQ2/DQ8 testing can help exclude genetic risk. Management involves gastroenterology referral, assessing nutrient deficiencies and bone health, and starting a gluten-free diet only after confirmation.

High tissue transglutaminase (tTG) antibody usually indicates an autoimmune response to gluten, most commonly celiac disease. It suggests intestinal inflammation and possible villous damage, though other autoimmune or inflammatory conditions can also raise tTG. Correlate results with symptoms and total IgA level. Confirmatory testing—gastroenterology evaluation and duodenal biopsy (or repeat testing after gluten challenge)—is recommended before starting a lifelong gluten‑free diet.

To confirm celiac disease, continue eating gluten and get serologic testing (anti‑tissue transglutaminase IgA plus total IgA; use IgG tests if IgA deficient). If serology is positive, refer for upper endoscopy with duodenal biopsy to show villous atrophy. HLA‑DQ2/DQ8 testing can exclude it if negative. Diagnosis is supported by symptom and serologic improvement on a gluten‑free diet.

IgG (immunoglobulin G) is the most abundant antibody in blood and extracellular fluid, produced by plasma cells after infection or vaccination. It provides long-term adaptive immunity, can cross the placenta, and helps neutralize pathogens. IgG blood tests assess immune status, past exposure or vaccine response, and can indicate chronic infection, autoimmune disease, or immunodeficiency when levels are abnormal.