Coeliac disease

Definition

• Also known as “gluten sensitive enteropathy”
• Common immune mediated malabsorptive condition
• Abnormal response to Gliadin (component of Gluten)
• Associated with flattening of the small intestinal villi

Incidence

• Mainly European – 1/1000
• (NB: Ireland 1/300)
• Most common cause of malabsorption

Aetiology

• Genetics
  • Immune disorder triggered by environmental agent (gluten) in predisposed individuals
• Association with HLA-DQ2 & HLA-DQ8
  • Human Leukocyte Antigens
  • Convey susceptibility
  • Over 99% affected individuals have one of these
• Risk Factors
  • Family history
  • 2-5% of 1st degree relatives develop symptomatic Coeliacs
  • Strong association with other auto-immune disorders
    • Type 1 DM
    • Autoimmune Thyroiditis
    • Also – Down Syndrome, Turner Syndrome, Pulmonary Haemosiderosis

Clinical Presentation

• Childhood Presentation
  • Present at 1-2 yrs
  • Previously well then failure to thrive
  • May have
    • Diarrhoea
    • Irritability
    • Poor appetite
  • May have
    • Iron deficiency
    • Short stature
    • FHx
    • Abdo distension
    • Clubbing
• Adult Presentation
  • Iron-deficiency
    • or combined Iron & Folate deficiency
  • Weight loss
  • Diarrhoea
  • Abdo discomfort (pain rare)
  • Borborygmi
  • Bloating
  • Associations:
    • Hyposplenism
    • Dermatitis Herpetiformis
      • “Coeliac Disease of the skin”
      • Vesicular, crusted, intensely pruritic lesions develop
      • Located on the back, buttocks, and elbows
      • Secondary infection common

Pathology

• Involves an abnormal cellular (T-cell mediated) & humoral response to gliadin
• Gliadin is a component of gluten (in wheat, barley), which acts as an epitope that the body reacts to
  • Causing mucosal damage
• Get
  • Loss of brush border enzymes
  • Loss of stimulus for pancreatic & bile secretion
  • Low pancreozymin & secretin
  • Exudation of protein across denuded mucosa
  • Protein losing enteropathy

Histology

• Macroscopically:
  • Mucosal Atrophy
  • Flattening of mucosal folds
  • Fissure, scalloping, prominent submucosal vascularity
• Histological changes
  • Increased intra-epithelial lymphocytes
  • Villous atrophy / “clubbing”
  • Hypertrophy of crypts
  • Attempt to increase cell production

Normal A. Coeliac B

Complications

• Increased risk for lymphoma and GI cancers
• Uncertain whether compliance to gluten-free diet influences rate of cancer
• Lymphoma the most common
• GI cancers include
  • Oesophageal SCC
  • Small Intestine Adenocarcinoma
  • Colorectal
  • HCC
  • NB: Significantly reduced risk of Breast Cancer

Investigations

• All testing for coeliac disease should be done when a patient is on a gluten-containing diet
• If low probability, screen with serology first, if negative, stop
• If high probability, do both serology and OGD
• Serological blood tests
  • IgA anti-Tissue Transglutaminase antibody (anti-tTG)
    • Specific test, good NPV
  • IgA anti-Endomysial antibodies (EMA)
    • Highest diagnostic accuracy
    • Costly and not as widely available as anti-tTG
  • IgA & IgG anti-Gliadin antibodies (AGA)
    • IgA more specific (97%), but poor sensitivity (71%)
    • IgG less specific (87%) but more sensitive (87%)
• Endoscopy – if positive serologic testing or high suspicion
  • To confirm the diagnosis
  • Need at least 4 x biopsies of post-bulbar duodenum

Management

• Strict gluten-free diet
• Avoid wheat, rye, and barley
• NB: Oats are ok

Follow-up

• Repeat biopsy at 3-4 months after dietary treatment
• Check mucosal improvement