Coeliac Disease

Introduction

Coeliac disease is an autoimmune disorder which is characterized by gluten sensitivity. It is a widely spread gastroenterological condition affecting both children and adults all around the world.

It is estimated that in the UK, around 1% of the population are affected by coeliac disease.

Women are more likely to be affected and account for two-thirds of cases.

The diagnosis of coeliac disease is seen in two different peak age periods. The first peak occurs in infancy when children start being exposed to solid foods containing gluten, while the second and larger peak occurs between 40-50 years old. However, coeliac disease can appear anytime.

Aetiology

In coeliac disease, gliadin, a component of gluten, isn't broken down sufficiently, and passes through the intestinal epithelial layer, prompting an immune response.

Gliadin binds to HLA DQ2 or DQ8 which activates T-cells in the intestinal mucosa and causes an immune response resulting in chronic inflammation and malabsorption of the small bowel.

Most patients with coeliac disease are HLA DQ2 positive as well as many being DQ8 positive.

Risk factors

There are a few risk factors for coeliac disease and their estimated occurrence is listed below:

• Genetics (around 70% if monozygotic twin affected)
• Autoimmune thyroid disease (15%)
• Genetic syndromes e.g. Down's and William's syndrome (up to 12%)
• Type 1 diabetes mellitus (8%)
• IgA deficiency (7%)

Clinical features

History

The signs and symptoms in coeliac disease may vary slightly between adults and children.

Coeliac disease in children is usually associated with:⁶

• Failure to thrive (stunted growth, growth chart faltering)
• Chronic diarrhoea
• Constipation (coeliac disease should be considered whenever diagnosing idiopathic constipation)
• Abdominal bloating
• Irritability
• Features of anaemia (adolescents)

Children typically present with these symptoms in the early years of life after being exposed to gluten products.

Coeliac disease in adults is normally seen with:³

• Long-standing diarrhoea (may be intermittent in nature)
• Nausea and vomiting
• Fatigue (patients often have underlying iron-deficiency anaemia)
• Weight loss

Other important areas to note:

• Family history: coeliac disease often runs in families and those with an affected first-degree family member have around a 10% chance of developing it.⁷
• Associated conditions: there are a range of conditions that, if present, would increase the risk of coeliac disease. These conditions are listed below.Conditions associated with Coeliac Disease
• Mnemonic: “I Don’t Take Apples, I Take Oranges”
• I: IgA deficiency
• D: Down's Syndrome
• T: Turner's Syndrome
• A: Autoimmune thyroid disease and autoimmune hepatitis
• I: IgA nephropathy
• T: Type 1 diabetes mellitus
• O: Other autoimmune conditions (e.g. Sjögren's, myasthenia gravis, Addison's disease)
• Clinical Examination
• The clinical features of coeliac differ between children and adults. All children and adults who present with features of coeliac disease should receive a thorough clinical examination.
• Clinical features that may be identified in children with coeliac disease include:
• Failure to thrive (though less common in the modern western diet)
• Abdominal distension
• Abdominal pain
• Muscle wasting, usually affecting the buttocks
• Signs of anaemia in adolescents (e.g. angular cheilitis, fatigue, pallor)
• Clinical features that may be identified in adults with coeliac disease include:
• Signs of anaemia
• Mouth ulcers
• Weight loss (though not usually significant)
• Anxiety features
• Joint pain
• Abdominal pain
• Dermatitis herpetiformis
• Extra-Intestinal Manifestations of Coeliac Disease
• Coeliac disease can cause a range of extra-intestinal manifestations. These should be kept in mind when taking a medical history and performing examinations:
• Arthritis
• Dermatitis herpetiformis
• Osteoporosis/osteopenia
• Infertility
• Ataxia
• Epilepsy
• Anxiety
• Depression
• Investigations
• The diagnosis of coeliac disease is based on immunological investigation results and the histology of small bowel biopsies.
• Coeliac features are often non-specific and many patients have mild to moderate disease, making diagnosis difficult. A gluten-free diet is not recommended as a diagnostic tool. All patients with suspected coeliac disease should receive an antibody screen followed by a duodenal biopsy if appropriate.
• In the UK, the average time to diagnosis from first symptoms is around 13 years.
• Laboratory Investigations
• Anti-tissue transglutaminase (TTG) antibodies and total IgA count: anti-TTG antibodies are diagnostic of coeliac disease if strongly positive. A total IgA count is necessary as an underlying IgA deficiency can cause false-negative results, hiding coeliac disease. If TTG is 10 times the upper limit of normal, a positive endomysial antibody (EMA) screen is also required.
• IgG endomysial antibodies (EMA), IgG deamidated gliadin peptide (DGP) or IgG TTG: IgG EMA, IgG DGP or IgG TTG can be used to diagnose coeliac disease in those who are IgA deficient. Performing these tests first-line is not recommended.
• Genetic HLA DQ2 and DQ8 screen: in the UK, positive genetic testing is currently also necessary. However, this is likely to change in the future as many patients who are HLA DQ2 and DQ8 positive do not have coeliac disease.
• In children, if TTG, EMA and genetic testing is positive, a duodenal biopsy is not required and the diagnosis of coeliac disease can be made.
• Duodenal Biopsy
• If the serology markers are positive, a small bowel biopsy is carried out by gastroenterology to confirm the diagnosis.
• Four Key Changes Seen on Duodenal Biopsy in Coeliac Disease
• There are four key changes that are seen on duodenal biopsy in those with coeliac disease:
• Presence of villous atrophy leading to a flat mucosa
• Crypt cell hyperplasia
• Intraepithelial cell lymphocytosis
• Inflammatory cell infiltration of the lamina propria
• The villous atrophy and the immunology findings used to diagnose coeliac disease often normalise following the removal of gluten from the diet. Therefore, those who have removed gluten from their diet and request testing cannot be tested. It is recommended to reintroduce gluten into the diet and return in 6-8 weeks if a formal diagnosis is necessary.
• Differential Diagnoses
• A range of conditions can present in a similar fashion to coeliac disease and should be considered during a diagnostic workup.
• Coeliac Disease
• Coeliac Disease is a common gastrointestinal disorder caused by sensitivity to gluten. Common symptoms include diarrhoea, abdominal bloating and features of malnutrition.
• Diagnosis
• Diagnosis is achieved by serology (anti-tissue transglutaminase antibodies) and biopsy (duodenum).
• Main Differentials
• Anorexia nervosa
• Bacterial overgrowth of the small bowel
• Crohn's disease
• Irritable bowel syndrome
• Lactose intolerance
• Autoimmune enteropathy
• Management
• Children with suspected coeliac disease should be referred to a paediatric gastroenterologist or an appropriate paediatrician with a special interest in gastroenterology.
• There are two key aspects of management in coeliac disease:
• Lifelong gluten-free diet: foods containing gluten include rye, wheat, barley and oats. Dietetic input may be required and should be considered case by case.
• Immunisation: individuals with coeliac disease often have functional hyposplenism (defective immune response) and therefore require pneumococcal vaccines every 5 years. Yearly influenza vaccines may be given to patients, however, this is on a case by case basis.
• Follow-up
• Patients with coeliac disease should be followed up annually reviewing weight, height, ongoing symptoms and the need for dietetic input. In those with ongoing symptoms, IgA tTG measurements can be carried out to check for compliance with a gluten-free diet. Adults with well-controlled disease may be followed up less frequently.
• Complications
• Untreated disease can result in numerous complications including:
• Hyposplenism (anatomical or functional)
• Iron deficiency anaemia
• Malnutrition
• Osteoporosis
• Small bowel T-cell lymphoma
• Vitamin B12 and folate deficiency (you may see mixed anaemia if iron deficiency is also present)
• Key points
• Coeliac disease is a common gastrointestinal disorder caused by a sensitivity to gluten.
• Common symptoms include diarrhoea, abdominal bloating and features of malnutrition.
• Diagnosis is achieved by serology (anti-tissue transglutaminase antibodies) and biopsy (duodenum).
• Treatment is with a life-long gluten-free diet.
• Complications include malignancy of the small bowel, hyposplenism and malnutrition.
• Causes of Coeliac Disease
• Coeliac disease has been linked to a range of pathological causes. The NHS website states that coeliac disease is caused by a reaction to gluten, a protein found in wheat, barley, and rye.
• A 2008 study by Barker and Liu found that coeliac disease involves an abnormal immune response to gluten, which leads to damage of the small intestine's villi, resulting in malabsorption of nutrients.
• The 2015 guidance from the National Institute for Health and Care Excellence (NICE) states that genetic factors are also important in the development of coeliac disease, specifically the genetics of the individual's immune system.
• Kamboj and Oxentenko's 2017 study also found that there is a range of factors that must be taken into account in the diagnosis and management of coeliac disease, such as associated autoimmune conditions.
• In addition to these causes, Presutti et al. 2008 and Caio et al. 2019 report that coeliac disease may result from complications such as anemia and osteoporosis. The NHS website also states that these complications can lead to further health problems if not monitored and managed properly.