What does tTG-IgA mean?
tTG-IgA measures the main IgA antibody used when coeliac disease is suspected. It is checked with total IgA so an IgA deficiency does not hide the signal.
What it shows and why it matters
tTG-IgA, or Tissue Transglutaminase IgA, measures antibodies against Tissue Transglutaminase and is the main first-line blood marker used when coeliac disease is suspected. A raised result can support the need for further coeliac assessment while the person is still eating gluten. Total IgA is checked alongside it because IgA deficiency can make a tTG-IgA result falsely low.
How tTG-IgA appears on your report
Look for Tissue Transglutaminase IgA (tTG-IgA). It may also be printed as tTG-IgA. The result is normally shown in U/mL, next to the reference interval used by the laboratory that ran the test.
Note the collection date before you compare it with anything, along with the context that matters for this marker: gluten exposure, Total IgA, age, assay method and immune treatment can affect it. Reducing gluten before testing can make the result falsely reassuring.
tTG-IgA range in Australia
Vector shows an assay-dependent contextual tracking band of 0.0–7.0 U/mL for tTG-IgA. It is not a universal optimal target or clinical threshold; use the interval printed by the laboratory that performed the test.
This contextual band mirrors the app and the Vector Profile; the performing laboratory’s interval remains authoritative.
Interpretation limits
tTG-IgA supports a coeliac assessment only when Total IgA and adequate gluten exposure make the result interpretable. Starting a gluten-free diet before assessment can undermine confirmation.
The interval printed beside your result remains the authority for that specimen. Reference intervals, diagnostic thresholds, treatment targets and Vector's tracking bands answer different questions and should not be substituted for one another.
What to read alongside tTG-IgA
A single marker rarely explains itself. These results are commonly interpreted together with tTG-IgA, and Vector keeps them within reach of each other as your record grows.
When to discuss tTG-IgA with a clinician
Take a raised result to your GP or gastroenterology clinician before removing gluten. Total IgA, symptoms and confirmatory testing determine the next step.
Tracking tTG-IgA over time
One tTG-IgA result is a single point. Import the report into Vector, check the extracted value, unit and collection date, and it becomes the start of a series instead — with each later report adding a dated point you can actually compare against.
Further reading
tTG-IgA is read the same way every other result on the report is. These two guides cover that method rather than this marker:
- How to read an Australian pathology report — A practical guide to dates, units, reference intervals and the context that belongs beside an Australian pathology result.
- Pathology report reference ranges: what they mean — Understand the laboratory interval, Australian guidance and the product context Vector adds to a result over time.
Common questions
What is a normal tTG-IgA range in Australia?
Australia has no nationally harmonised reference interval for tTG-IgA, so the range printed on your report varies with the laboratory and assay. Vector shows 0.0–7.0 U/mL as an assay-dependent contextual tracking band, not a universal optimal target or clinical threshold. Always use the interval beside your own result.
How should the tTG-IgA tracking band be interpreted?
Vector shows 0.0–7.0 U/mL as an assay-dependent contextual band for tTG-IgA. It is not a universal optimal target or clinical threshold. Interpret the result with the performing laboratory's interval, treatment and symptoms.
What unit is tTG-IgA reported in on Australian pathology reports?
tTG-IgA is usually reported in U/mL on Australian pathology reports. The performing laboratory prints a reference interval in the same unit beside the result, and that interval is the one that governs your individual result.
What can change your tTG-IgA result?
Gluten exposure, Total IgA, age, assay method and immune treatment can affect it. Reducing gluten before testing can make the result falsely reassuring.
What else is tTG-IgA called?
Tissue Transglutaminase IgA (tTG-IgA) may also appear as tTG-IgA on a pathology report. Laboratories differ in the label they print, which is why Vector matches on several names for the same analyte.
Sources
- RCPA Manual: Coeliac diseaseAustralian guidance on tTG-IgA, ongoing gluten exposure and Total IgA testing.
- RCPA Manual: Pathology TestsAustralian pathology context and laboratory-interval guidance.
Published 29 August 2026 · Updated 29 August 2026 · Author Vector