Tissue Transglutaminase Antibody (tTG) Test

What is a tissue transglutaminase test?

Tissue transglutaminase test(also known as IgA Anti-tTG test, celiac disease testing and IgA anti-tissue transglutaminase test)is a serological test used for screening and detecting celiac disease and a related skin disorder dermatitis herpetiformis. It is an enzyme-linked immunosorbent assay (ELISA) test that measures the presence of tissue transglutaminase (tTG)-IgA antibodies in the blood. Transglutaminase is an enzyme present in our body and is involved in protein metabolism

Why has my doctor ordered the tTg test for me?

Your physician may order a tTG test for you if you present with the following signs or symptoms-

– Persistent diarrhea or constipation
– Longstanding nausea/vomiting
– Pain abdomen (considered a classic sign of coeliac disease)
– Abdominal cramping or a sense of bloating

If you suffer from celiac disease, you may also present with-

– Unexplained weight loss
– Lethargy
– Infertility or recurrent fetal loss
– Itchy skin rash (dermatitis herpetiformis)
– Loss of tooth enamel/bone density
– Psychiatric ailments
– Nerve disorders

In children, this malabsorptive disorder may manifest as failure to thrive. Adults suffer from mineral/vitamin deficiencies. A tTg test is also indicated in asymptomatic subjects if-

– They have a family history of celiac disease.

– They suffer from an associated autoimmune disorder (e.g.type 1 diabetes mellitus, autoimmune thyroid disease, autoimmune liver disease, Down syndrome).

What is a celiac disease?

Celiac disease (also known as gluten-sensitive enteropathy or celiac sprue) is an autoimmune disorder triggered by gluten peptides present in grains (rye, barley, wheat).  Individuals who carry HLA-DQ2 or -DQ8 markers in their genetic make-up form antibodies directed against their own bodies.

The resulting immune-mediated inflammatory process leads to villous atrophy of the mucosa of the small intestine. The ensuing malabsorption due to the destruction of small intestinal mucosa leads to the signs and symptoms outlined earlier. However, the symptoms unrelated to the gastrointestinal system are often more distressing for the patient.

Depending on the predominant clinical symptoms, celiac disease has been divided into subgroups, namely-classical, silent, atypical, refractory and non-responsive celiac disease.

What is dermatitis herpetiformis?

Dermatitis herpetiformis (also known as Duhring disease or Duhring-Brocq disease) is an extremely itchy blistering skin condition seen in 15-25% of patients suffering from celiac disease. It is an autoimmune disorder considered by many to be the integumentary manifestation of celiac disease.

Can I undergo a tTg test if I am pregnant?

Yes, you can undergo a tissue transglutaminase test even if you are pregnant or breastfeeding your child.

Can children undergo the tTg test?

Children 3 years and above can safely undergo this test. The results of the test may not be accurate if it is performed in younger children.

Do I need to fast before a tTg test?

There is no need to fast before this test. You can continue to eat and drink normally. Make sure that you do not stop consuming gluten diet prior to taking this test because the results may be negative if you do so.

How should I prepare for a tTg test?

No specific preparations are required before you undertake a tTG test. Inform your physician if you suffer from a coagulopathy or have been taking blood thinners. As it is a blood test, a vein on your arm will be punctured by a fine needle to draw blood. You might experience, pain and subsequently, bruising, bleeding or infection at the site of invasion. If you are faint-hearted, you might feel dizziness. It is better to look away when the blood sample is being withdrawn in such a case.

How is a tTg test performed?

– A tissue transaminase test is performed as an outpatient procedure. It is a safe, minimally invasive and quick test.

– No sedation is given. The test can be carried out in a doctor’s office or at a diagnostic center.

– The technician will apply a tourniquet proximally to the site chosen for venipuncture. This makes the veins more prominent, allowing easier access.

– The area is cleaned with a disinfectant. A sterile needle is used to puncture the vein and draw about 5 ml of blood. The pressure is applied to the vein with sterile gauze after the needle is withdrawn.

– The tourniquet is released. The blood sample is collected in a vial.

– A small bandage is applied over the site from where blood has been drawn.

How long does a tTg test last?

A tissue transglutaminase test lasts only around 5-10 minutes. In the case of a child, obese or a geriatric patient, venous access may be difficult leading to more than one prick.

When can I get the results of my test?

It can take 5 – 7 days for the results of a tTG test to be out. However, some laboratories claim that they can provide you the results of the test the same day.

What should I do if I test positive?

The tissue transglutaminase test measures the level of Tissue Transglutaminase (tTG) Antibody in blood. The results can be as follows-

What are the foods that I need to avoid if I suffer from celiac disease?

The cereals wheat, barley, and rye contain gluten and need to be avoided at all costs. The common foods that contain gluten include-breads, pasta, sauce, biscuits, cakes, pastries, and pies.

What are the gluten-free foods available in the market?

Though the thought of leading a life restricting yourself to certain food items only may seem frightening at first, there is a wide variety of gluten-free foods available-fish, meat, chicken, eggs, beans, rice, fruits, vegetables, soya, and many more. Your physician will give you an extensive list of the foods that you need to avoid and that which you can safely consume.

Is there any cure for celiac disease?

There is no cure for celiac disease. It is a lifelong disorder. However, the disease can be kept in check by avoiding a gluten-free diet. Your intestine will show signs of healing within a few weeks of abstinence from gluten diet. Complete recovery from the damage inflicted on the intestinal mucosa may, however, take up to 2 years. It is to be kept in mind that the symptoms will return if you consume gluten at any stage.

What does a tTg test cost in India?

The cost of a tTg test in India ranges from Rs 1000-15000, across different cities and lab facilities.

What are the advantages and limitations of a tTg test?

What are the other tests to detect celiac disease?

Celiac disease is a chronic disease which if undetected leads to high morbidity and mortality. Though there is no cure for this debilitating illness, early detection and timely intervention can arrest the progress of this disease. Apart from the tTG-IgA test, some other diagnostic tests available are-

Total serum IgA test– It checks an individual for IgA deficiency. If found positive, the Ttg-IgG test is performed.

Endomysial antibody test (EMA)– An expensive test, it measures the levels of IgA endomysial antibody using primate esophagus or human umbilical cord.

Deamidated gliadin peptide test– It is performed in patients suffering from IgA deficiency or those testing negative for the above two tests.

Video capsule endoscopy– Macroscopic changes in the intestinal mucosa can be visualized.

X-ray– Radiological examination of the small intestinal may reveal dilatation or thickening of the walls, suggesting celiac disease.