These findings show a clear need to standardise coeliac blood testing across the UK. Aligning ULN thresholds, improving access to total IgA and EMA or alternatives like DGP, and clearer guidance would reduce variation. The no‑biopsy pathway only works when testing is consistent.

The no biopsy pathway depends on IgA tTG results being consistent across labs. But because assays use very different ULN thresholds, the same result can lead to different diagnoses, creating a risk of misclassification. The diagram below shows how this can happen.

Turnaround times ranged from 24 hours to 3 weeks. Total IgA testing varied widely, from 0% in Scotland to over 70% in northern and southwestern regions. EMA was available in about 80% of sites but uneven due to cost, workload and user dependence.

Across UK labs, 12 different IgA tTG tests were used. ULN thresholds ranged from 3–30 IU/mL, even with the same manufacturer. This ten fold gap means the same result can lead to different diagnoses, echoing findings in Australasia (Glennan et al., 2025).

A UK wide phone survey included NHS trusts and health boards offering coeliac testing. Of 342 sites, 96% responded. Among them, 165 sent samples to external labs and 177 tested in house, with 131 providing full data for analysis.

This shift puts major importance on accurate, consistent IgA tTG testing, making it vital to understand how reliably UK labs perform these tests. A national survey examined how accessible and consistent coeliac blood testing is across the country.

In 2020, ESPGHAN introduced a no biopsy option for diagnosing coeliac disease. When IgA tTG levels are at least ten times the normal limit, evidence shows diagnosis is highly reliable and often preferred by patients and clinicians (Werkstetter et al., 2017).

Many people with coeliac disease remain undiagnosed or misdiagnosed (Conrad et al., 2023). Diagnosis once relied on a small bowel biopsy, where doctors examined tissue for gluten related damage. This was long considered the “gold standard” for confirming the condition.

Coeliac disease is an autoimmune condition where gluten triggers the immune system to damage the small intestine, causing inflammation and poor nutrient absorption. This reaction only occurs in genetically predisposed people (Coeliac Australia, n.d.).

SAME BLOOD SAMPLE, DIFFERENT LAB, DIFFERENT DIAGNOSIS.
As the UK adopts no biopsy coeliac testing, inconsistent IgA tTG results could leave patients with unequal answers. Without reliable, standardised testing, your diagnosis may depend on where your sample is analysed.
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