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Coeliac Disease

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Overview

Coeliac disease is an autoimmune systemic disorder primarily affecting the small intestine. It is provoked by gluten in susceptible individuals and can lead to malabsorption. Gluten is a protein found in wheat, barley, and rye. Its pathophysiology is not entirely known and it is thought that its aetiology is multifactorial, including genetic and environmental factors.

Epidemiology

  • Coeliac disease may have an incidence rate of around 14 per 100,000 per year
  • Its incidence has 2 peaks; one shortly after weaning with gluten in the first 2 years of life, and the other in adolescence to 30 years

Risk Factors

  • Family history
  • Immunoglobulin A (IgA) deficiency
  • Type 1 diabetes
  • Autoimmune liver disease
  • Autoimmune thyroid disease
  • Human leukocyte antigen (HLA)-DQ2 and HLA-DQ8

Presentation

Overview

The symptoms of coeliac disease may be vague:

Associated conditions

Patients may present with complications of coeliac disease or associated conditions:

  • Unexplained depression or anxiety
  • Unexplained peripheral neuropathy
  • Unexplained ataxia
  • Unexplained subfertility or recurrent miscarriage
  • Unexplained persistently slightly elevated AST/ALT on liver function testing
  • Unexplained hyposplenism
  • Dermatitis herpetiformis – a rash associated with a transglutaminase enzyme in the skin

Differential Diagnoses

Inflammatory bowel disease (IBD)

  • There may be a history of bloody diarrhoea, rectal bleeding, perianal disease, fever, and abdominal tenderness
  • Symptoms do not correlate with gluten consumption

Irritable bowel syndrome (IBS)

  • Consists of abdominal pain, bloating, and changes in bowel habits with no rectal bleeding or unintentional weight loss
  • Abdominal pain is often relieved by defecation
  • Symptoms do not correlate with gluten consumption

Small bowel bacterial overgrowth syndrome

  • May present similarly to IBS
  • No unintentional weight loss is seen
  • Symptoms do not correlate with gluten consumption

Investigations

When to screen

The following patients should be offered screening for coeliac disease:

  • Persistent unexplained gastrointestinal symptoms
  • Unexplained weight loss, faltering growth, or failure to thrive
  • Severe or persistent mouth ulcers
  • Unexplained iron-deficiency, B12, or folate deficiency
  • Patients with associated conditions:
    • Type 1 diabetes mellitus (T1DM) – should be done at the time T1DM is diagnosed
    • Autoimmune thyroid disease – at the time it is diagnosed
    • Irritable bowel syndrome
    • Dermatitis herpetiformis
    • 1st-degree relatives with coeliac disease

Screening should be considered if any of the following are present:

  • Metabolic bone disorders
  • Unexplained peripheral neuropathy or ataxia
  • Unexplained complications in pregnancy, including recurrent miscarriage and subfertility
  • Unexplained persistently elevated liver AST/ALT
  • Down’s syndrome
  • Turner syndrome
  • Dental enamel defects

Screening and diagnosis

  • Coeliac serology testing – used as screening:
    • Only valid if patients continue eating gluten for a minimum of 6 weeks before testing is done
    • This does not diagnose coeliac disease. It is used to decide whether further assessment is necessary.
    • 1st-line: serum IgA tissue transglutaminase antibody (tTGA) + total IgA
      • Total IgA is measured because, in some individuals with an IgA deficiency, this may return a negative result
    • 2nd-line: IgA endomysial antibody (EMA) if IgA tTGA is unavailable
      • Consider re-testing if a person presents with new symptoms of coeliac disease, despite previous serology
  • Referral to gastroenterology and endoscopic intestinal biopsy:
    • The gold standard diagnostic test
    • Biopsies are generally done in the duodenum and jejunum
    • Findings suggesting coeliac disease are:
      • Crypt hyperplasia
      • Villous atrophy
      • Intraepithelial lymphocytosis
      • Infiltration of the lamina propria with lymphocytes

Other investigations

HLA testing:

  • Not recommended for use in initial diagnosis
  • This is because some people with susceptible HLA types may never go on to develop coeliac disease
  • Generally done in a specialist setting under certain circumstances (e.g. people who cannot undergo a biopsy and do not have a gluten challenge)

Management

Overview

  • 1st-line: lifelong gluten-free diet
  • Monitoring with IgA tTGA or IgA EMA may be considered to assess compliance
  • Offer annual influenza vaccine and 5-yearly pneumococcal vaccine:
    • Around 1/3 of patients with coeliac disease have hyposplenism, predisposing them to pneumococcal infection. This is thought to be due to functional hyposplenism and splenic atrophy

Patient Advice

  • Foods that contain gluten include:
    • Those based on wheat, barley, or rye
    • Those that may be contaminated with gluten
    • Those that contain malt, including beer
  • Alternatives sources of starch that may be eaten include:
    • Rice
    • Potatoes
    • Corn

Complications

  • Anaemia:
    • Secondary to malabsorption of iron, B12, and folate 
  • Failure to thrive and delayed puberty:
    • Secondary to malabsorption
  • Hyposplenism:
    • Due to functional hyposplenism and splenic atrophy
    • Seen in 1/3 of patients with coeliac disease
  • Metabolic bone disease – osteomalacia, osteopenia, or osteoporosis:
    • Due to malabsorption of vitamin D and calcium
  • Lactose intolerance:
    • Due to bowel damage due to inflammation
  • Malignancy:
    • Such as Hodgkin’s and non-Hodgkin’s lymphomas, such as enteropathy-associated T-cell lymphoma (EATL), bowel adenocarcinoma, and pancreatic cancer 
  • Problems with pregnancy:
    • Including subfertility and recurrent miscarriage
  • Refractory coeliac disease:
    • Rare and seen in around 1% of cases
    • Where symptoms and villous atrophy persist despite avoiding gluten
  • Reduced quality of life:
    • Due to coeliac disease itself and the social implications of adhering to a gluten-free diet
  • Psychiatric problems:
    • Including depression, anxiety, and eating disorders

Prognosis

  • The resolution of symptoms and degree of duodenal recovery do not correlate
  • Most patients have a complete solution of symptoms on a gluten-free diet alone
  • Symptoms tend to improve within weeks of starting a gluten-free diet, however, it can take up to 2 years for the gastrointestinal tract to recover

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