Coeliac Disease

Autoimmune disorder resulting from a heightened immune response to gluten-derived proteins.

Background and Epidemiology

• Immune-mediated, inflammatory disorder caused by gluten.  Gluten may be found in wheat, rye and barley products
• Prevalence of ~0.8-1.9%.  Thought that up to 85% of patients with coeliac disease are undiagnosed.
• Slightly more common in females (2:1)

Aetiology

• Polygenic factors
  • Most commonly associated with HLA-DQ2 and DQ8 (whilst these tend to be sensitive, they are not specific i.e. much of the general population also have these alleles)
  • Family hereditability (10-15% if a 1st degree relative; 70% in identical twins)

Pathophysiology

• Gliadin (a product of gluten) is thought to be de-aminated by tissue transglutaminases in the gut cell.  This is thought to increase its antigenicity.
  • Negatively charged gliadin is thought to activate the immune system directly (IL-15 -> NK cell and lymphocyte proliferation and recruitment)

Clinical Presentation

• Can present at any age (including old age).  Many patients can be largely asymptomatic
  • Can present shortly after weaning in babies
    • Diarrhoes (frequent, pale stools) or occasionally constipation; vomiting; weight loss/anorexia, irritability and failure to thrive
    • Children may present with a growth problem
  • In older children/adults
    • Anaemia (due to folate/iron deficiency)
    • Abdominal discomfort, arthralgia, fatigue and malaise
    • Diarrhoea, steatorrhoea
    • Mouth ulcers and angular stomatitis (mainly due to anaemia and vitamin deficiencies)
    • Occasionally, dermatitis herpetiformis
• Patients may have an associated autoimmune disease e.g.
  • T1DM
  • Thyroid disease
  • Primary Biliary Cirrhosis
  • Sjogrens Syndrome
  • IgA deficiency

Investigations

• Blood tests
  • FBC
    • Anaemia is common (microcytic- iron-deficient)
  • U&Es
    • Hypokalaemia, hypocalcaemia, hypomagnesaemia and metabolic acidosis may be present, as can signs of malnutrition e.g. hypoalbuminaemia
  • Before testing specifically for Coeliac, confirm the patient has been eating gluten-containing foods (at least twice a day for past 6 weeks)
    • Initial blood tests include
      • IgA tissue transglutaminase antibody (tTGA; first line according to NICE) or IgA endomysial antibody (EMA)
      • It can be useful to measure serum IgA also to rule out any false negatives (if IgA is low, test for specific IgGs)
• Most patients will also have endoscopic tissue biopsy to confirm coeliac by immunofluorescence
  • Villous atrophy and lymphocytic infiltrate can also be seen under microscopy
  • NB Prior to tissue biopsy, gluten should be reintroduced into the diet for a minimum of 6 weeks to increase the chance of true positive (decrease false negative)

Management

• Gluten free diet is the mainstay of management.  (Often referral to a dietician or self-help information/resources is extremely useful)
• Management of associated sequalae may be useful e.g. vitamin/iron replacement
• Follow up should involve measuring coeliac serology (as well as other bloods)

Prognosis/Complications

• Patients are at higher risk of T-cell lymphoma, small bowel carcinoma and other GI cancers
• Patients with poor disease control are also at higher risk of osteoporosis and should be managed where appropriate to prevent its development

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