Tissue Transglutaminase Ab IgG (tTG-IgG)

What is Tissue Transglutaminase Ab IgG (tTG-IgG)?

Measures IgG antibodies to tissue transglutaminase, used mainly for celiac evaluation in people with low total IgA.

Tissue transglutaminase IgG (tTG-IgG) antibodies are checked in celiac disease evaluation, particularly for people who have selective IgA deficiency, a condition that can make the more commonly used tTG-IgA test unreliable. This marker relates to the immune system and digestive tract, reflecting an abnormal immune reaction to gluten. Clinicians typically order tTG-IgG when a person has digestive symptoms suggestive of celiac disease but a known or suspected low total IgA level, or when IgA-based testing results seem inconsistent with the clinical picture. As with IgA-based testing, tTG-IgG is most accurate while gluten continues to be eaten regularly. A positive result is generally followed by further evaluation, which may include a small intestine biopsy, to help confirm a celiac disease diagnosis.

Lifestyle factors that influence this marker

• Continue a normal, balanced diet including gluten unless advised otherwise before testing
• Support digestive health with a variety of whole foods, fiber, and adequate hydration
• Maintain regular meal patterns
• Address any known nutrient gaps through food-first approaches
• Avoid smoking, which is linked with broader digestive tract irritation

Tests often checked alongside this

• Tissue Transglutaminase IgA (tTG-IgA) — the primary celiac screening test this complements
• Total IgA — helps clarify why IgG-based testing was used
• Deamidated Gliadin Peptide (DGP) Antibody — another antibody sometimes used in IgA-deficient individuals
• Complete blood count — can reveal anemia linked with malabsorption

How this can show up in how you look and feel

• May be associated with digestive symptoms such as bloating or diarrhea
• May be associated with fatigue or nutrient deficiencies
• May be associated with unintended weight changes in some individuals

What can affect this marker

• Age
• Diet (gluten intake at time of testing)
• Inflammation
• Lab variability between testing methods

What to track over time

• Whether antibody levels decline over time if a gluten-free diet is followed
• How this result fits with total IgA and biopsy findings, if performed
• Repeat testing may be considered periodically to monitor dietary response

What to ask your doctor

• Why was the IgG version of this test used instead of tTG-IgA?
• Do I need further evaluation, such as a biopsy, based on this result?
• Was I eating enough gluten before this test for accurate results?
• How should this result inform any dietary changes?

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