Coeliac

Question 1

What is coeliac?

Answer 1

Type 4 Hypersensitivity
AI - T cell mediated inflammation of mucosal lining of the small bowel and upper GIT in response to prolamins / gluten (wheat, barley, oats) resulting in villous atrophy and crypt hyperplasia

Question 2

What is the pathophysiology of coeliac?

Answer 2

Most pathogenic component of gluten is gliadin.

Gliadin is endocytosed/absorbed across gastric mucosa

Gliadin once in is deamidated by tissue transglutaminase tTG and endocytosed across gastric mucosa

Deamidated and non-demitted peptides are phagocytosed by APC and presented via (mhc class 2) HLA DQ2/DQ8 to T helper cells - triggers immune response (IgA mediated)

IgA attack tTG on the intestinal lining leading to tissue damage and inflammation:

-> villous atrophy + crypt hyperplasia and intraepithelial lymphocyte infiltration
- severe malabsorption

Question 3

What are the risk factors of coeliac?

Answer 3

HLA associated : HLA DQ2/ DQ8
Other autoimmune diseases: T1DM (all are tested for ceoliac even if asx), autoimmune thyroid, Addisons
IGA deficiency - as IgA is natural response to ingested gluten and bind to them preventing absorption - less gluten triggering coeliac

Question 4

what are the clinical presentations of coeliac?

Answer 4

Often Asx

Malabsorption due to villous atrophy:

Indigestion
Diarrhoea (watery) Steatorrhea - cant absorb fat
Anaemia - less Fe/B23/Folate
Osteomalacia (can’t absorb vitamin D)

Abdo bloat/discomfort
Constipation
Unintentional wt loss
Fatigue
Failure to thrive - kids
Aphthous ulcers
Dermatitis herpetiformis - (IgA skin depositions causing blistering rash

+ rare Nx - peripheral neuropathy /ataxia/eplipsy

Question 5

Complications of untreated coeliac disease

Answer 5

Vitamin deficiency
Anaemia
Osteoporosis

Increased risk of malignancy:
Enteropathy-associated T-cell lymphoma

Question 6

Investigations for coeliac disease

Answer 6

1st Line:
Total IgA
IgA tTg AB
- very sensitive and specific
-false - associated with IgA def

Can also test for IgA endomysial antibody (anti-EMA) and IgG anti-tTG but less sensitive

Gold standard: Endoscopy + duodenal biopsy

Classic findings include 1) villous atrophy;
2) crypt hyperplasia;
3) an increase in intraepithelial lymphocytes
4) lamina propria infiltration with lymphocytes

Question 7

Managing coeliac

Answer 7

correct deficiencies - supplementations
+
Gluten Free diet
+
Dapsone for dermatitis herpetiformis