2026 British Society of Gastroenterology Guidelines on Adult Coeliac Disease

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Reference: September 2026 | Issue 9 | Vol 12 | Page 23

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In July, the British Society of Gastroenterology (BSG) issued an updated guideline on adult coeliac disease (CD).

The 2026 BSG Guidelines on the Diagnosis and Management of Adult Coeliac Disease were prompted by recent advancements in relation to CD. The previous update to the guidelines was issued in 2014. Since then, over 4,000 studies on adult CD have been published.

The 2026 guideline shifts adult CD management away from a rigid, procedure-heavy model to a flexible, risk-stratified, and patient-centric approach. The document provides more robust, specific criteria for seronegative, potential, and ultra-short coeliac disease, along with a clear, step-by-step diagnostic and treatment roadmap for refractory coeliac disease (RCD) types 1 and 2.

Diagnosis

The guidelines continue to recommend that patients consume a gluten-containing diet prior to testing for CD. For patients who have already started a gluten-free diet (GFD) prior to diagnostic testing, a daily intake of 3-6g of gluten for at least six weeks is sufficient.

IgA-tTG antibody testing is recommended as the first-line investigation for CD. A positive result should be followed by referral to secondary care. IgG-based coeliac serology and upper GI endoscopy with duodenal biopsies is recommended for individuals with selective IgA deficiency (sIgAD) and clinical suspicion for CD. sIgAD is defined as isolated total serum IgA level <0.07g/L.In individuals with marginally low total serum IgA (serum IgA >0.2g/L). IgG-coeliac serology testing is not warranted.

At least four biopsies should be taken from the second part of the duodenum (D2) and two biopsies from the duodenal bulb (D1). D1 and D2 biopsies should be placed in separate pathology pots. Where possible, a single-bite biopsy technique should be employed to acquire duodenal tissue samples.

HLA-typing should not be used as an initial diagnostic test for CD, but it may be useful in certain scenarios, such as patients who have started a GFD before formal CD testing, those with coeliac-like changes on duodenal biopsies but negative coeliac serology, and individuals with suspected CD who do not respond to a GFD.

A diagnosis of CD requires positive coeliac serology and duodenal biopsies demonstrating increased intra-epithelial lymphocytes (>25/100 epithelial cells) and crypt hyperplasia with/without villous atrophy. Histological manifestations of gluten-induced mucosal inflammation may appear as subtle changes in villous height to crypt ratio and/or overt villous atrophy. Duodenal lymphocytosis in isolation is not specific to CD.

A diagnosis of potential CD can be made in patients with persistently positive coeliac serology, biopsies demonstrating no or isolated increase in intraepithelial lymphocytes (IELs), and a positive HLA-DQ2 and/or HLA-DQ8 genotype. A diagnosis of seronegative CD can be made in patients without elevated coeliac serology (including IgG-based tests), but with villous atrophy, a positive HLA-DQ2 or HLA-DQ8 genotype, and improvement on a GFD.

A diagnosis of CD should not be made in the case of negative coeliac serology and duodenal biopsies demonstrating an isolated increase in IELs (duodenal lymphocytosis) and other causes should be explored.

In a significant change, the 2026 guideline advises that a diagnosis of CD can be made without duodenal biopsies in the secondary care setting in symptomatic adults with IgA-tTG titre ≥10× ULN. However, the guidelines committee stresses that this ‘no-biopsy’ pathway is optional and should be adopted only after shared decision-making with the patient.

Endoscopy remains important in patients with red-flag symptoms or when alternative diagnoses are suspected. Other conditions that can lead to transient increases in tTG antibody levels include Crohn’s disease, autoimmune enteropathy, food allergies, multiple sclerosis, and thyroiditis.

The following symptoms should prompt CD testing:

• Persistent unexplained abdominal or gastrointestinal symptoms
• Prolonged fatigue
• Unexpected weight loss
• Severe or persistent mouth ulcers
• Unexplained iron, vitamin B12, or folate deficiency.

Testing should be considered in people with unexplained neurological symptoms (particularly peripheral neuropathy or ataxia); dental enamel defects; persistently raised liver enzymes with unknown cause; unexplained subfertility or recurrent miscarriage; and metabolic bone disease.

If available, HLA genotyping should be considered before undertaking a gluten challenge, as this may avoid the need for further diagnostic testing. If a gluten challenge is required, a dose of 3-6g of gluten daily for at least six weeks is advised.

Treatment

A life-long GFD is the only current recommended treatment for CD, although there are no randomised placebo-controlled trials evaluating the long-term health impact of the GFD in CD. Up to a third of patients continue to have persistent symptoms despite reporting adherence to a GFD. Small bowel enteropathy improves with adherence to a GFD, although the timespan of mucosal healing is variable and typically takes one-two years or longer. A GFD may reduce the risk of complications such as low bone mineral density and lymphoproliferative malignancy.

People with CD commonly present with haematinic and/or vitamin deficiencies at diagnosis. There is limited evidence to support specific recommendations on routine haematinic or micronutrient supplementation. Patients should be assessed and monitored for deficiencies in iron, folate, vitamin B12, vitamin D, and calcium at diagnosis and during follow-up, and supplemented if clinically indicated.

All patients diagnosed with CD should undergo regular follow-up for up to two years after diagnosis. Repeat duodenal biopsies should be considered in the long term. Patients who have responded well to a GFD may be considered for patient-initiated follow-up. Long-term systematic follow-up is advised for patients who are poorly adherent to the GFD or are at risk of poor adherence and for those who do not respond adequately or develop complications.

There is no data supporting routine follow-up biopsies in adult CD in the absence of new or persisting signs or symptoms, or patient preference.

All newly diagnosed adult patients should have a DXA scan one year after starting a GFD. A repeat DXA scan should be performed in individuals with persistent villous atrophy and/or RCD after two-three years.

CD is associated with an increased risk of pneumococcal infection, which may, in part, be linked to hyposplenism. Hence, it is recommended that all adult patients with CD receive the pneumococcal vaccination. Those with RCD and/or on long-term immunosuppressive medication should receive a booster after five years.

Conclusion

The 2026 BSG guidelines contain updated recommendations in a number of areas. Most significantly, it introduces an optional no-biopsy diagnostic pathway for selected adults, moving away from the strict 2014 requirement of mandated endoscopy and duodenal biopsy for every adult diagnosis.

Furthermore, the new guideline offers expanded guidance on complex or non-classic presentations, including potential, seronegative, IgA-deficient, ultra-short (bulb-limited), and refractory CD. The 2026 guidance also includes a more tailored, risk-based follow-up strategy focused intensely on the first two years, plus patient-initiated follow-up options for long-term support.