The Small Intestine - Coeliac Disease

Question 1

What is Coeliac Disease?

Answer 1

Intolerance to Gluten - a protein (in particular Gliadin, the alcohol-free fraction of Gluten). It is an autoimmune condition which triggers inflammation in the small intestine.

Question 2

Give 3 Gluten-Containing Carbohydrates.

Answer 2

1. Wheat (Bread, Pasta, Pastries).
2. Barley (Beer; Whisky - Malted Barley).
3. Rye.

Question 3

Give 3 Gluten-Free Carbohydrates.

Answer 3

1. Rice.
2. Potatoes.
3. Corn (Maize).

Question 4

Risk Factors of Coeliac Disease (8).

Answer 4

1. Genes : HLA-DQ2 (95%) and HLA-DQ8 (80%) Haplotypes cause inappropriate activation of intestinal T cells.
2. Family History of Coeliac Disease/Autoimmune Conditions.
3. Type I Diabetes Mellitus.
4. Thyroid Disease.
5. Autoimmune Hepatitis.
6. Primary Biliary Cirrhosis.
7. Primary Sclerosing Cholangitis.
8. Down’s Syndrome.

Question 5

Epidemiology of Coeliac Disease (3).

Answer 5

1. 1% of UK population.
2. Bimodal Peak (Childhood and 50-60).
3. Kids present before age of 3 (introduction of cereals).

Question 6

Pathophysiology of Coeliac Disease (8).

Answer 6

1. Gluten is digested by luminal and brush border enzymes into amino acids and peptides e.g. Gliadin (33 amino-acid peptide).
2. Gliadin is deaminated in the mucosa by tTG.
3. Anyone with HLA-DQ2/8 will have this deaminated Gliadin closely fitting the MHCII grooves and so is presented to Th Cells by APCs.
4. Tc cells are generated against Gliadin.
5. Tc cells migrate into intestinal epithelium as intraepithelial lymphocytes to damage and destroy epithelial cells.
6. Progressive Villous Atrophy.
7. Compensatory : Hyperplasia of Crypt Cells.
8. Humoral Response : Anti-tTG, Anti-EMA.

Question 7

Investigations of Coeliac Disease (General Points) (5).

Answer 7

1. Low-Threshold (since patients can be asymptomatic).
2. Stool Culture (exclude infection).
3. Patients must be taking Gluten for 6 weeks prior to testing (to detect antibodies/inflammation).
4. 1st Line : Serology.
5. Gold Standard : Endoscopy and Duodenal Biopsy (after positive serology or high suspicion despite negative serology).

Question 8

Clinical Features of Coeliac Disease (5).

Answer 8

1. Symptoms of Malabsorption e.g. Diarrhoea, Steatorrhoea, Weight Loss, Failure to Thrive (Short Stature, Wasted Buttocks), Fatigue.
2. IBS-like Symptoms e.g. Altered Bowel Habit, Abdominal Pain, Abdominal Distension.
3. Non-Specific Symptoms e.g. Anaemia (Folate, Iron, B12).
4. Dermatitis Herpetiformis (intensely pruritic blistering papulovesicular lesions over extensor surfaces, buttocks, abdomen).
5. RARELY - neurological symptoms e.g. epilepsy, neuropathy, cerebellar ataxia.

Question 9

Serology in Coeliac Disease (6).

Answer 9

1. Total IgA (make sure there is no IgA deficiency - false negative).
2. IgA anti-tTG (high sensitivity and negative predictive value) or use IgG anti-tTG (if they have IgA deficiency).
3. If IgA is weakly positive, IgA EMA antibodies are used.
4. Can use anti-DGPs (Deaminated Gliadin Peptide Antibodies) but not recommended by NICE.
5. Some patients also have anti-Casein antibodies.
6. These antibodies are found in levels proportional to the intensity of the condition.

Question 10

Endoscopy and Duodenal Biopsy Findings in Coeliac Disease (5).

Answer 10

1. Villous Atrophy.
2. Crypt Hyperplasia.
3. Prominent Intraepithelial Lymphocytes.
4. Damage to Small Bowel Mucosa.
5. Must be performed on all adults to confirm diagnosis.

Question 11

Anaemia in Coeliac Disease (3).

Answer 11

1. Microcytic Anaemia (Iron Deficiency).
2. Normocytic Anaemia (Chronic Inflammation).
3. Macrocytic Anaemia (Folate Deficiency).

Question 12

Blood Results in Coeliac Disease (3).

Answer 12

1. FBC = Anaemia.
2. LFTs = Hypoalbuminaemia.
3. U&Es = Reduced Vitamin D Absorption (so DEXA).

Question 13

Relationship between Type I Diabetes Mellitus and Coeliac Disease.

Answer 13

All patients with a new diagnosis of Type I Diabetes Mellitus are tested for Coeliac Disease.

Question 14

Management of Coeliac Disease (3).

Answer 14

1. Only Effective Treatment : Life-Long Gluten-Free Diet.
2. Serology and Histology reverses on gluten-free diet.
3. Pneumococcal Vaccine (degree of functional hyposplenism) every 5 years.

Question 15

Complications of Coeliac Disease (4).

Answer 15

1. Micronutrient Deficiency = Folic Acid, Vitamin B12, Vitamin D, Calcium.
2. Bone Disease : Osteopenia (Calcium).
3. EATL : Enteropathy-Associated T Cell Lymphoma (which can also complicate to Non-Hodgkin Lymphoma).
4. Hyposplenism.