Tissue Transglutaminase (tTG) Antibody (IgG)

The Tissue Transglutaminase (tTG) Antibody (IgG) test contains 1 test with 1 biomarker.

Brief Description: The Tissue Transglutaminase IgG Antibody test is a specialized blood test used to diagnose and monitor celiac disease, an autoimmune disorder that affects the small intestine's ability to absorb nutrients from food. This test specifically measures the levels of IgG antibodies against tissue transglutaminase (tTG) in the blood.

Collection Method: Blood Draw

Specimen Type: Serum

Test Preparation: No preparation required

When and Why the Test May Be Ordered:

A healthcare provider may order the Tissue Transglutaminase IgG Antibody test when celiac disease is suspected:

• Celiac Disease Symptoms: It is ordered when an individual shows symptoms like diarrhea, weight loss, fatigue, abdominal pain, and malabsorption.
• Screening: It is used as a screening tool for individuals with a family history of celiac disease or those with related autoimmune conditions.

What the Test Checks For: The Tissue Transglutaminase IgG Antibody test checks for the presence of IgG antibodies against tissue transglutaminase. Transglutaminase is an enzyme found in the tissues, and its interaction with gluten triggers an immune response in individuals with celiac disease. Elevated IgG antibody levels indicate an autoimmune reaction to gluten.

Other Lab Tests That May Be Ordered Alongside:

When a tTG-IgG test is ordered, it's often part of a broader evaluation for celiac disease and related conditions. Here are some tests commonly ordered alongside it:

1. Tissue Transglutaminase IgA Antibody (tTG-IgA):

   • Purpose: To detect antibodies against tissue transglutaminase in the IgA class.
   • Why Is It Ordered: tTG-IgA is the primary screening test for celiac disease and is more sensitive in individuals with normal IgA levels.

2. Total Serum IgA:

   • Purpose: To measure the level of Immunoglobulin A (IgA) in the blood.
   • Why Is It Ordered: To check for selective IgA deficiency, which can lead to false-negative results in IgA-based celiac disease tests.

3. Endomysial Antibody (EMA) IgA:

   • Purpose: To detect antibodies that target the endomysium, a component of the intestine.
   • Why Is It Ordered: EMA IgA is highly specific for celiac disease and is often used to confirm positive tTG-IgA or tTG-IgG results.

4. Deamidated Gliadin Peptide (DGP) Antibodies (IgG and IgA):

   • Purpose: To detect antibodies against deamidated gliadin peptides.
   • Why Is It Ordered: DGP tests can be useful in certain cases where tTG or EMA tests are inconclusive, especially in children under 2 years of age.

5. Complete Blood Count (CBC):

   • Purpose: To evaluate overall blood health.
   • Why Is It Ordered: To assess for signs of anemia or other blood cell changes that can be associated with celiac disease due to malabsorption.

6. Iron Studies:

   • Purpose: To evaluate iron status.
   • Why Is It Ordered: To assess for iron deficiency anemia, a common complication of celiac disease due to malabsorption in the damaged small intestine.

7. Vitamin and Mineral Levels (such as Vitamin D, B12, Folate):

   • Purpose: To measure levels of key vitamins and minerals.
   • Why Is It Ordered: To evaluate for deficiencies common in celiac disease due to malabsorption.

8. HLA-DQ Genotyping:

   • Purpose: To identify genetic markers associated with celiac disease.
   • Why Is It Ordered: To assess genetic susceptibility to celiac disease, especially in ambiguous diagnostic cases.

These tests, when ordered alongside a Tissue Transglutaminase IgG Antibody test, provide a comprehensive assessment of potential celiac disease. They are crucial for diagnosing the condition, understanding its impact on the patient's health, and guiding dietary and treatment strategies. The specific combination of tests will depend on the individual’s symptoms, family history, and risk factors.

Conditions or Diseases Requiring the Test: The Tissue Transglutaminase IgG Antibody test is primarily used for diagnosing celiac disease, an autoimmune disorder triggered by gluten consumption. It is not suitable for non-celiac gluten sensitivity.

How Health Care Providers Use the Results:

• Diagnosis: Elevated IgG antibodies against tissue transglutaminase, along with clinical symptoms, can lead to a diagnosis of celiac disease.
• Treatment Monitoring: After a gluten-free diet is initiated, the test can be used to monitor adherence and response to treatment.
• Exclusion of Celiac Disease: A negative test result, along with other clinical and genetic factors, can help exclude celiac disease as the cause of symptoms.

In conclusion, the Tissue Transglutaminase IgG Antibody test plays a crucial role in diagnosing celiac disease. By detecting IgG antibodies against tissue transglutaminase, healthcare providers can accurately identify individuals with autoimmune reactions to gluten, allowing for timely treatment and dietary adjustments.

Most Common Questions About the Tissue Transglutaminase IgG Antibody test:

Clinical Utility and Interpretation

What is the primary purpose of the Tissue Transglutaminase IgG Antibody test?

The Tissue Transglutaminase IgG Antibody test is primarily used to aid in the diagnosis of celiac disease, especially in individuals who are IgA deficient. Tissue transglutaminase is an enzyme targeted by these antibodies in patients with celiac disease.

How are the results of the Tissue Transglutaminase IgG Antibody test interpreted?

Positive results from the Tissue Transglutaminase IgG Antibody test indicate that the patient may have celiac disease, especially if they show relevant clinical symptoms. However, further confirmatory tests, like a small intestinal biopsy, are often needed to confirm the diagnosis. Negative results reduce the likelihood of celiac disease, but it's essential to interpret results in the context of the overall clinical picture.

Clinical Applications and Diagnoses

Why would someone get the Tissue Transglutaminase IgG Antibody test instead of the IgA version?

Some individuals are deficient in Immunoglobulin A (IgA). For them, the Tissue Transglutaminase IgA Antibody test might produce false-negative results even if they have celiac disease. Therefore, in suspected IgA deficient patients, the IgG version of the test is preferred.

Besides celiac disease, are there any other conditions associated with elevated Tissue Transglutaminase IgG antibodies?

Yes, while the Tissue Transglutaminase IgG Antibody test is highly associated with celiac disease, elevated levels can also be seen in other conditions, including liver diseases, other gastrointestinal diseases, and certain autoimmune disorders.

Comparative Insights

How does the Tissue Transglutaminase IgG Antibody test compare to other tests for celiac disease?

The Tissue Transglutaminase IgG Antibody test is just one of several tests used to help diagnose celiac disease. Other tests include the Tissue Transglutaminase IgA Antibody test, Endomysial IgA antibodies, and Deamidated gliadin peptide (DGP) antibodies. While the Tissue Transglutaminase tests (both IgA and IgG) are commonly used due to their sensitivity, no single test is definitive, and a combination of tests, along with a small intestinal biopsy, provides the most accurate diagnosis.

Understanding Limitations and Challenges

Can someone with normal Tissue Transglutaminase IgG Antibody levels still have celiac disease?

Yes, it is possible. While the Tissue Transglutaminase IgG Antibody test is sensitive, no test is perfect. Some patients with celiac disease might test negative, especially if they're on a gluten-free diet when tested or if they have selective IgA deficiency and are not tested with the IgG version. Thus, the test's results should be considered alongside clinical symptoms and other diagnostic tests.

Additional Questions and Insights

Is it necessary to be on a gluten-containing diet before taking the Tissue Transglutaminase IgG Antibody test?

Yes, it's recommended that individuals continue consuming a gluten-containing diet before the test. Being on a gluten-free diet can cause the antibody levels to decrease, potentially leading to false-negative results. If someone has been on a gluten-free diet for an extended period, they might need to undergo a "gluten challenge" before testing to obtain accurate results.

If someone has positive Tissue Transglutaminase IgG Antibody results but a negative biopsy, how is this discrepancy resolved?

If there's a discrepancy between the serological test and the biopsy, it might be due to various reasons, including patchy intestinal damage that the biopsy missed, early celiac disease with serological positivity but no histological changes yet, or other conditions that raise antibody levels. In such cases, clinical judgment, periodic re-evaluation, and sometimes genetic testing for celiac disease-associated genes (HLA DQ2/DQ8) can provide clarity.

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.