Tissue Transglutaminase IgA (TTG) Test: Purpose, Normal Range and Price

The Tissue Transglutaminase IgA test, commonly referred to as the TTG IgA test, is a blood test that detects IgA class antibodies directed against tissue transglutaminase, an enzyme involved in cross-linking proteins within the intestinal lining. These antibodies are produced when genetically susceptible individuals consume gluten, a protein found in wheat, barley, and rye, triggering an abnormal autoimmune response that damages the villi of the small intestine and impairs nutrient absorption. The TTG IgA test is the single most recommended first-line serological investigation for celiac disease, endorsed by international gastroenterological and paediatric societies worldwide. It combines high sensitivity and specificity, making it the most reliable non-invasive screening tool available before proceeding to confirmatory small intestinal biopsy. In India, celiac disease has historically been considered a disease of North Indian wheat-consuming populations, particularly in Punjab, Haryana, and Uttar Pradesh, though growing clinical awareness is revealing its broader prevalence across the country. Beyond celiac disease, elevated TTG IgA antibodies are increasingly recognised in other autoimmune and inflammatory conditions. The test requires the patient to be consuming a gluten-containing diet at the time of testing to ensure accurate results, as antibody levels fall significantly once gluten is eliminated. The test is performed on a small blood sample drawn from a vein and completed in under five minutes.

Doctors prescribe a TTG IgA test in the following situations: Diagnosing celiac disease in patients with chronic diarrhoea, bloating, abdominal pain, and malabsorption symptoms where TTG IgA is the recommended first-line serological test that reliably identifies autoimmune gluten intolerance before intestinal biopsy is pursued for histological confirmation. Investigating unexplained iron deficiency anaemia, folate deficiency, and osteoporosis in adults where undiagnosed celiac disease causing chronic malabsorption is a frequently overlooked underlying cause, particularly in patients who do not report prominent gastrointestinal symptoms. Evaluating children with failure to thrive, short stature, delayed puberty, and recurrent abdominal pain where celiac disease is a well-established cause of impaired growth and nutritional deficiency in the paediatric age group in India. Screening individuals with a first-degree family history of celiac disease where the risk of the condition is significantly elevated and early serological screening enables diagnosis before overt nutritional deficiencies and intestinal damage develop. Assessing patients with Type 1 diabetes, autoimmune thyroid disease, Down syndrome, and Turner syndrome where celiac disease co-occurs at substantially higher rates than in the general population and routine periodic TTG IgA screening is clinically recommended. Monitoring dietary compliance in diagnosed celiac patients on a gluten-free diet where falling TTG IgA levels over time confirm adherence to dietary treatment and persistent elevation signals ongoing gluten exposure requiring dietary review.

The TTG IgA test measures the concentration of IgA antibodies against tissue transglutaminase in the blood, expressed in Units per millilitre (U/mL). The normal reference range is less than 20 U/mL, though threshold values may vary slightly between laboratory platforms. Normal (Below 20 U/mL) A result below 20 U/mL is considered negative for TTG IgA antibodies, making celiac disease unlikely in a patient consuming a regular gluten-containing diet. However, a negative result in a patient with selective IgA deficiency, a condition that falsely lowers TTG IgA, requires supplementary testing with TTG IgG or deamidated gliadin peptide antibodies. Mildly Elevated (20 to 100 U/mL) A mildly elevated result warrants clinical correlation and typically requires small intestinal biopsy for confirmation, as low-level positivity can occasionally occur in other inflammatory conditions. The treating gastroenterologist will advise whether to proceed directly to biopsy or retest after ensuring adequate gluten intake. Markedly Elevated (Above 100 U/mL) A markedly elevated TTG IgA above 100 U/mL, particularly above three times the upper limit of normal, is highly specific for celiac disease. In children with such high titres alongside compatible symptoms, current European paediatric guidelines support a diagnosis of celiac disease without mandatory biopsy when supported by clinical and genetic findings.

The single most important preparation requirement for the TTG IgA test is to continue consuming a normal gluten-containing diet in the weeks leading up to testing. Patients who have already self-initiated a gluten-free diet will have significantly reduced or normalised TTG IgA levels, leading to false negative results and missed diagnosis. Your doctor may advise a gluten challenge period before testing if dietary restriction has already begun. No fasting is required for this test, as food intake does not affect antibody concentrations. However, since TTG IgA testing is frequently ordered alongside a full blood count, iron studies, folate, and vitamin B12 as part of a malabsorption workup, fasting for 8 hours before collection is advisable to ensure all co-ordered tests yield accurate results. Inform your doctor if you have a known history of selective IgA deficiency, as this condition causes falsely low or negative TTG IgA results regardless of celiac disease status. In such cases, your physician will order complementary TTG IgG or deamidated gliadin peptide antibody tests to ensure accurate serological assessment. Staying well hydrated before the blood draw facilitates easier venous access and a smooth collection experience.

If you are booking through the SecondMedic platform the TTG IgA test price starts at approximately Rs. 1342. The exact price will be confirmed at the time of booking through SecondMedic. If your doctor has prescribed multiple tests alongside TTG IgA, SecondMedic health packages include TTG IgA as part of a broader celiac disease panel at a significantly lower combined price.

SecondMedic offers convenient home sample collection for the TTG IgA test, making it easy to get tested without visiting a diagnostic centre. Home collection is available free of charge for orders above Rs. 300. A trained phlebotomist will visit your preferred address between 7 AM and 10 PM, seven days a week, including Sundays and public holidays. Your blood sample is processed at NABL-accredited partner laboratories, and your report is delivered within 24 hours directly to your WhatsApp and email.