Coeliac disease (GI) Flashcards
What is coeliac disease?
Systemic autoimmune disease triggered by dietary gluten peptides found in wheat, rye, barley and related grains causing chronic intestinal malabsorption
What is the immune reaction in coeliac disease triggered by?
Gliadin - a component of gluten that patients with coeliac disease become intolerant to
What does immune activation in coeliac disease lead to? (3)
- villous atrophy
- hypertrophy of the intestinal crypts
- increased numbers of lymphocytes in epithelium and lamina propria
What conditions is coeliac disease associated with? (4)
- autoimmune thyroid disease
- dermatitis herpetiformis
- IBS/IBD
- T1DM
What is dermatitis herpetiformis, and how do we investigate and manage it? (4)
- itchy vesicular skin lesions on extensor surfaces (elbows, knees, buttocks)
- Ix - skin biopsy under direct immunofluorescence showing IgA deposition in granular pattern in upper dermis
- Rx - gluten-free diet
- Rx - dapsone
What markers is coeliac disease associated with? (2)
- HLA-DQ2
- HLA-DQ8
Describe the aetiology of coeliac disease?
- gluten peptides stimulate IL-15 production –> immune activation and epithelial damage
- gluten peptides are deaminated by tissue transglutaminase and bind to coeliac-associated HLA peptides (DQ2 or DQ8) which activates Th cells
- Th cells promote plasma cell maturation –> anti-tissue transglutaminase antibodies which attack villi, causing villous atrophy, hypertrophy of intestinal crypts and increased lymphocytes within epithelium and lamina propria
What deficiencies are patients with coeliac disease likely to have? (4)
- iron
- folate
- B12
- vitamin D
What are the clinical features of coeliac disease? (12)
- diarrhoea (osmotic) - chronic or intermittent, might also get steatorrhoea (pale, greasy, offensive-smelling stool due to malabsorption)
- bloating
- abdominal pain
- anaemia (signs of IDA)
- dermatitis herpetiformis (intensely itchy papulovesicular lesions on extensor surfaces)
- osteopenia/osteoporosis (vitamin D deficiency + hypocalcaemia)
- fatigue
- weight loss
- failure to thrive / faltering growth in children
- easy bruising (vitamin K deficiency)
- peripheral neuropathy
- ataxia
What are the features of a coeliac crisis? (5)
- hypovolaemia
- severe watery diarrhoea
- acidosis
- hypocalcaemia
- hypoalbuminaemia
What are some risk factors for coeliac disease? (6)
- Fx coeliac disease
- IgA deficiency
- autoimmune risk - T1DM, autoimmune thyroid disease, IBD
- HLA-DQ2/8 - although most never develop coeliac disease
- infancy or 4th/5th decade
- female
What are the first-line investigations for coeliac disease? (4)
- IgA-tTG antibodies
- FBC
- endomysial IgA
- small bowel endoscopy and histology (biopsy)
What is the first investigation we do for coeliac disease?
IgA-tTG = raised
When might you get a IgA-tTG false negative (coeliac disease)?
- might get a false negative if patient has IgA deficiency
- account for this via endomysial antibody (EMA) test to look for selective IgA deficiency = elevated
What other (less relevant) serology tests are there for coeliac disease? (2)
- anti-gliadin antibodies elevated - not recommended
- anti-casein antibodies in some patients
What is the gold standard test for coeliac disease diagnosis?
Endoscopic intestinal biopsy - done on all suspected patients to confirm/exclude diagnosis, needed to confirm diagnosis
Which part of small bowel is endoscopic biopsy done for coeliac disease?
Traditionally duodenum, but sometimes jejunum
What findings on small bowel endoscopy and biopsy indicate coeliac disease? (5)
- villous atrophy
- crypt hyperplasia/hypertrophy
- scalloping of mucosal folds with increase in intra-epithelial lymphocytes
- lamina propria infiltration with lymphocytes
- mosaic pattern of mucosa
What might you see in FBC in coeliac disease? (2)
- microcytic hypochromic RBCs (anaemia)
- IDA or folate/B12 deficiency
Which patients should be screened for coeliac disease?
Patients with unexplained iron-deficiency anaemia
What would a blood smear show for coeliac disease? (3)
- target cells & Howell-Jolly bodies due to functional hyposplenism
- microcytic hypochromic RBCs
When would a skin biopsy be done for coeliac disease?
If any lesions suggest dermatitis herpetiformis
What is important for coeliac disease investigations in terms of patients’ gluten intake?
Patients must have eaten gluten for at least 6 weeks before they are tested for antibodies or biopsy, or else they may be negative
What are some differential diagnoses for coeliac disease? (11)
- peptic duodenitis (chronic/recurrent abdo pain related to eating)
- Crohn’s disease
- giardiasis (diarrhoeal illness)
- small-intestinal bacterial overgrowth
- post-gastroenteritis
- tropical sprue
- immunodeficiency states
- Graft-vs-Host disease
- autoimmune enteropathy
- drug-induced enteropathy
- non-coeliac gluten sensitivity (no villous atrophy)
