What Does a High t-Transglutaminase (tTG) IgG Marker Mean?

When reviewing your lab results, seeing a high t-Transglutaminase (tTG) IgG marker can be concerning — but what does it actually mean?

This antibody test is most commonly used in the evaluation of celiac disease and gluten sensitivity. Understanding the role of tTG IgG, its limitations, and how it fits into the bigger picture of diagnosis can help you make sense of your results.

What Is t-Transglutaminase (tTG)?

Tissue transglutaminase (tTG) is an enzyme found in many tissues of the body, especially in the intestines. In people with celiac disease, the immune system mistakenly targets this enzyme when gluten (a protein found in wheat, rye, and barley) is consumed.

This autoimmune reaction leads to:

Production of tTG antibodies (IgA and/or IgG)
Damage to the small intestine lining
Malabsorption of nutrients

What Does the IgG Form Measure?

IgA vs. IgG: The standard screening test for celiac disease is usually tTG-IgA, because it is more specific and accurate in most cases.
tTG-IgG is often measured when:
- A person has IgA deficiency (a relatively common condition, more frequent in celiac patients).
- Doctors want additional confirmation alongside other markers.

So, a high tTG IgG result can provide supporting evidence of gluten-related immune activity, especially if IgA testing cannot be relied upon.

Causes of a High tTG IgG

Celiac disease (most common reason)
- Suggests the immune system is reacting to gluten, damaging intestinal tissue.
Non-celiac gluten sensitivity (less common)
- May trigger mild elevations but without intestinal destruction.
Other autoimmune or inflammatory conditions
- In rare cases, elevated tTG IgG can occur in chronic liver disease, type 1 diabetes, or other autoimmune conditions.

Limitations and Risk Communication

It’s important to understand:

Not diagnostic on its own: A high tTG IgG doesn’t confirm celiac disease by itself.
False positives are possible: Other autoimmune diseases or intestinal inflammation can sometimes raise levels.
Follow-up is essential: Diagnosis usually requires:
- Additional antibody tests (e.g., tTG-IgA, total IgA, deamidated gliadin peptide (DGP) antibodies)
- And/or a small intestine biopsy to confirm villous atrophy.

Never self-diagnose based on this test alone — always discuss results with a gastroenterologist or your primary care provider.

Inclusivity Considerations

Children: Testing in children often includes both IgA and IgG forms, as IgA deficiency is more common.
IgA deficiency: Up to 2–3% of people with celiac disease have IgA deficiency, making tTG-IgG especially important in these cases.
At-risk groups: Those with type 1 diabetes, Down syndrome, or a family history of celiac disease may benefit from both IgA and IgG testing.

What To Do If Your tTG IgG Is High

Do not eliminate gluten right away before further evaluation — this can interfere with confirmatory testing.
Consult your doctor or a gastroenterologist to discuss additional tests.
Consider genetic testing (HLA-DQ2/DQ8) if celiac disease remains unclear.
Work with a healthcare provider before starting or maintaining a gluten-free diet.

The Bottom Line

A high t-Transglutaminase (tTG) IgG marker may indicate celiac disease, particularly if you have IgA deficiency or are at higher risk. However, it is not definitive on its own and should be interpreted in context with other lab markers, clinical symptoms, and possibly a biopsy.

Track and understand your antibody results with HealthMatters.io — your partner in making lab results more accessible and actionable.

FAQ

Q: Is tTG IgG the same as tTG IgA?
A: No. tTG IgA is the standard screening test; tTG IgG is mainly used when IgA is deficient or inconclusive.

Q: Can you have high tTG IgG but not have celiac disease?
A: Yes, though less common — other autoimmune or inflammatory conditions can sometimes cause elevations.

Q: Should I go gluten-free if my tTG IgG is high?
A: Not yet. Removing gluten before full testing can prevent an accurate diagnosis. Always consult your doctor first.

Medical Disclaimer

This article is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider regarding your test results or health conditions.