Tissue Transglutaminase (tTG) Antibody IgG Biomarker Testing
It checks IgG antibodies to tissue transglutaminase to support celiac evaluation, with easy ordering and Quest-based lab access through Vitals Vault.
With Vitals Vault, you have access to a comprehensive range of biomarker tests.
The Tissue Transglutaminase (tTG) Antibody IgG test looks for an immune response that can happen in celiac disease, a condition where gluten triggers inflammation and damage in the small intestine.
This marker is especially useful when standard celiac screening is less reliable, such as when you have IgA deficiency or when your clinician is trying to complete the picture after mixed or borderline results.
Your result does not diagnose celiac disease by itself. It is one piece of evidence that is usually interpreted alongside symptoms, diet history, and other labs, and sometimes followed by confirmatory testing.
Do I need a Tissue Transglutaminase (tTG) Antibody IgG test?
You might consider a tTG IgG test if you have ongoing symptoms that could fit celiac disease, such as chronic diarrhea or constipation, bloating, unexplained weight loss, iron-deficiency anemia, persistent fatigue, or nutrient deficiencies that do not have a clear cause.
This test is commonly used when IgA-based celiac tests may not be dependable. For example, if you have known or suspected IgA deficiency, a negative tTG IgA can be falsely reassuring, and IgG-based testing can help your clinician keep the evaluation on track.
It can also be helpful if you have autoimmune conditions (such as type 1 diabetes or autoimmune thyroid disease) where celiac disease is more common, or if you have a strong family history and want objective screening.
Testing supports clinician-directed care rather than self-diagnosis. If you are already avoiding gluten, talk with your clinician before testing because antibody levels can fall on a gluten-free diet and make results harder to interpret.
This is a laboratory immunoassay performed in a CLIA-certified lab; results support clinical evaluation and are not a standalone diagnosis of celiac disease.
Lab testing
Ready to order tTG Antibody IgG and review it with your clinician?
Schedule online, results typically within about a week
Clear reporting and optional clinician context
HSA/FSA eligible where applicable
Get this test with Vitals Vault
With Vitals Vault, you can order tTG Antibody IgG testing without a referral and complete your blood draw at a participating lab location.
Once your results are in, PocketMD can help you understand what “negative,” “borderline,” or “positive” means in plain language and what follow-up questions to bring to your clinician, especially if you are deciding whether you need additional celiac markers or a retest.
If you are tracking symptoms over time, Vitals Vault makes it easy to re-order the same test so you can compare trends, including after diet changes or treatment decisions made with your care team.
- Order online and complete your draw at a nationwide lab network
- PocketMD guidance for next steps and companion tests
- Easy re-testing to track changes over time
Key benefits of Tissue Transglutaminase (tTG) Antibody IgG testing
- Helps evaluate celiac disease when IgA-based screening may be unreliable (such as IgA deficiency).
- Adds evidence when symptoms suggest gluten-related intestinal inflammation but the picture is unclear.
- Supports earlier identification of celiac-related malabsorption patterns that can drive anemia or low nutrients.
- Helps guide whether you may need additional celiac antibodies or confirmatory testing with your clinician.
- Provides a baseline before treatment or diet changes so you can interpret future results more confidently.
- Can be used to monitor antibody trends over time when paired with clinical follow-up and diet adherence.
- Pairs well with PocketMD to translate results into practical next steps and retest timing.
What is Tissue Transglutaminase (tTG) Antibody IgG?
Tissue transglutaminase (tTG) is an enzyme found in many tissues, including the lining of the small intestine. In celiac disease, gluten exposure can trigger the immune system to form antibodies that target tTG.
The tTG Antibody IgG test measures the IgG class of antibodies directed against tTG. Many celiac screening strategies start with tTG Antibody IgA because it is highly informative for many people, but IgG testing becomes important when IgA is low or absent.
A positive tTG IgG result suggests your immune system is reacting in a way that can be seen in celiac disease, but it is not perfectly specific. Your clinician typically interprets it alongside other celiac markers, your total IgA level, your symptoms, and whether you are currently eating gluten.
Why IgG matters in celiac testing
If your body does not make enough IgA (selective IgA deficiency), IgA-based tests can be falsely negative even when celiac disease is present. In that situation, IgG-based tests (like tTG IgG and often deamidated gliadin peptide [DGP] IgG) can provide a more reliable signal.
What the test does not tell you
This test does not measure intestinal damage directly, and it cannot confirm celiac disease on its own. It also cannot tell you whether symptoms are due to non-celiac gluten sensitivity, irritable bowel syndrome, or another cause without additional evaluation.
What do my Tissue Transglutaminase (tTG) Antibody IgG results mean?
Low or negative tTG Antibody IgG
A low (often reported as negative) tTG IgG result means the lab did not detect a significant IgG antibody response to tissue transglutaminase. This lowers the likelihood of celiac disease, but it does not fully rule it out, especially if you have been eating little or no gluten. If your symptoms are strong or you have risk factors, your clinician may still consider total IgA testing and other celiac markers or a different diagnostic approach.
In-range tTG Antibody IgG (typical reference range)
Most labs report tTG IgG as negative, borderline/weak positive, or positive rather than an “optimal” wellness range. An in-range or negative result is generally reassuring when you are eating gluten regularly and your overall celiac workup is otherwise low risk. If you have IgA deficiency, your clinician may rely more heavily on IgG-based markers and your clinical picture. When symptoms persist, it is reasonable to discuss whether additional tests (such as DGP IgG or total IgA) would better match your situation.
High or positive tTG Antibody IgG
A high (positive) tTG IgG result means your immune system is producing IgG antibodies against tTG, which can be consistent with celiac disease. The higher the value and the more it aligns with other markers and symptoms, the more concerning it becomes. Your clinician may recommend confirmatory testing, which can include additional antibody tests, genetic risk testing (HLA-DQ2/DQ8), or an intestinal biopsy depending on your case. Do not start a gluten-free diet solely based on this result without guidance, because diet changes can complicate confirmation.
Factors that influence tTG Antibody IgG
Your current gluten intake is one of the biggest drivers of antibody levels; reducing or eliminating gluten can lower tTG antibodies over weeks to months. IgA deficiency is a key reason IgG testing is ordered, and it changes how your clinician weighs IgG results relative to IgA results. Other autoimmune or inflammatory conditions can sometimes be associated with nonspecific antibody positivity, which is why confirmation and context matter. Lab methods and cutoffs vary, so it is best to compare your value to the reference interval on your report and trend results using the same lab when possible.
What’s included
- Tissue Transglutaminase Ab, Igg
Frequently Asked Questions
What is the tTG IgG test used for?
tTG Antibody IgG is used to support evaluation for celiac disease, particularly when IgA-based tests may be less reliable. It can help clarify whether your immune system is reacting in a pattern that can occur with gluten-triggered intestinal inflammation.
Do I need to be eating gluten for this test to be accurate?
Usually, yes. If you have already reduced or eliminated gluten, antibody levels can fall and the test may be negative even if celiac disease is present. If you are gluten-free, ask your clinician whether a supervised gluten challenge or alternative testing makes sense before you draw labs.
What’s the difference between tTG IgA and tTG IgG?
They measure different antibody classes against the same target (tTG). tTG IgA is often the first-line screening test, while tTG IgG is especially helpful when you have IgA deficiency or when IgA results do not match your symptoms and risk factors.
If my tTG IgG is positive, does that mean I definitely have celiac disease?
Not necessarily. A positive result increases suspicion, but diagnosis typically requires correlation with symptoms, other antibody tests, and sometimes confirmatory procedures. Your clinician may recommend additional labs (like total IgA and DGP IgG) and discuss whether further evaluation is needed.
Can a negative tTG IgG rule out celiac disease?
A negative result makes celiac disease less likely, especially if you are eating gluten regularly. However, false negatives can occur if gluten intake is low, if testing is done early, or if your case requires different markers. Persistent symptoms should be evaluated even with negative antibodies.
How long after going gluten-free do tTG antibodies go down?
Antibody levels often decline over weeks to months, but the timeline varies by person and by how elevated the result was to begin with. If you are monitoring response, your clinician may suggest repeating testing after several months while also tracking symptoms and nutritional status.