CBL - Diarrhoea & Coeliac Disease

Question 1

What are the differential diagnoses for causes of diarrhoea? [5]

Answer 1

1. small bowel conditions: e.g. coeliac and small bowel crohn’s
   
   • typically causes watery diarrhoea
2. large bowel conditions: e.g. ulcerative colitis
   
   • typically includes blood and mucus
3. steatorrhoea
   
   • fat malabsorption, possibly associated with pancreatic insufficiency
4. infective gastroenteritis
   
   • caused by salmonella, campylobacter or shigella

Question 2

What are the possible causes of weight loss? [7]

Answer 2

1. malignancy
2. thyrotoxicosis
3. addison’s disease
4. poor diabetic control
5. infection (TB)
6. malabsorption
7. eating disorders

Question 3

What drugs could cause diarrhoea? [2]

Answer 3

1. metformin
2. proton pump inhibitors (PPI)

Question 4

What are the possible underlying causes of iron deficiency anaemia? [5]

Answer 4

1. Malignancy
2. Poor diet
3. Coeliac disease -> malabsorption
4. GI bleeding
5. Crohn’s/IBD
6. Menorrhagia (abnormal menstrual bleeding, if pre-menopause)

Question 5

What investigations should you carry out on a patient with suspected coeliac? [8]

Answer 5

1. Haematology
   
   • FBC/Haematinics/Blood Film/ESR
2. Biochemistry
   
   • U&Es/LFTs/Mg/Ca/TFTs/HbA1c (diabetic control)
3. Stool microbiology
   
   • (culture, C.diff toxin +/- ova, cysts and parasites)
4. Faecal Calprotectin
   
   • protein produced in the gut as a result of any inflammatory process
   • sensitive but non-specific test
   • can be elevated due to any cause of underlying inflammation (e.g. coeliac, NSAIDs, IBD or infection)
5. Faecal Elastase
   
   • elastase is a pancreatic enzyme, which helps to break down connective tissue and is present in the serum, urine and faces
   • pancreatic elastase does not undergo any significant degradation during intestinal transit and, therefore, acts as a useful marker of pancreatic activity.
   • low faecal elastase (<500) points to pancreatic exocrine insufficiency
6. Immunology
   
   • IgA TTG autoantibodies and IgA anti-endomysial autoantibodies
   • have reasonable sensitivity & specificity for coeliac
   • HLA typing: >95% of patients with coeliac disease are HLADQ2/8
     
     • (sensitive but non-specific test, useful in difficult cases)
7. CXR
   
   • to exclude malignancy or TB
8. upper GI endoscopy and duodenal biopsy
   
   • should take 4 biopsies from distal duodenum for maximal yield as changes may be patchy (must be on gluten-rich diet at time)

Question 6

Name two features of the wall of the normal small bowel that serve to increase the surface area available for transport [2]

Answer 6

1. plicae circulares
2. villous structure

Question 7

What are the histological features of coeliac disease seen on biopsy? [3]

Answer 7

1. crypt hyperplasia
2. sub-total villous atrophy
3. increase in intra-epithelial lymphocytes

Question 8

Describe the pathogenesis of coeliac disease [4]

Answer 8

1. Coeliac disease is due to autoimmune destruction of villous architecture due to gluten-hypersensitivity
2. Gluten products such as wheat/barley/rye cause an inflammatory hypersensitivity reaction against the mucosa of the small intestine.
3. There is some genetic susceptibility genes associated with coeliac disease (HLA-DQ2 and HLA-DQ8)
4. Inflammation of the mucosa is due to T cell infiltration and then proliferation. This leads to a flat mucosa with villous atrophy and crypt hyperplasia.
5. Decreased absorptive capacity will lead to decreased surface area -> malabsorption -> anaemia.

Question 9

What is the treatment for coeliac disease? [1]

Answer 9

gluten-free diet

Question 10

What conditions are associated with coeliac disease? [5]

Answer 10

1. Dermatitis Herpetiformis
2. Anaemia
3. Diabetes
4. Hyposplenism
5. Autoimmune thyroid disease