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Introduction to Clinical Biochemistry > L20-21 Gastrointestinal Disorders > Flashcards

L20-21 Gastrointestinal Disorders Flashcards

1
Q

What is a peptic ulcer?

A

A break in the mucus lining of the stomach or duodenum causes stomach acid to damage the epithelial lining

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2
Q

What are the main causes of peptic ulcers?

A

Helicobacter pylori infection (most common) and non-steroidal anti-inflammatory drugs (NSAIDS) or aspirin

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3
Q

How does Helicobacter pylori cause peptic ulcers?

A

Breaks down mucus layer and colonises stomach mucosa - allows acid to cause damage

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4
Q

How do NSAIDS (non-steroidal anti-inflammatory drugs) cause peptic ulcers?

A

They block cox-1, which is involved in prostaglandin and mucus production in stomach - cant form lining

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5
Q

What are the two main ways of diagnosing peptic ulcers?

A

Endoscopy or H. pylori testing

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6
Q

How can testing for H. pylori in relation to peptic ulcers be carried out?
(3)

A

Faecal antigen testing
Serum antibody quantitation
Carbon-13 urea breath test

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7
Q

What does the carbon-13 urea breath test test for?

How does this work?

A

H. pylori infection as a cause for peptic ulcers

Patient is given carbon-13 urea, H. pylori splits it into H2O and CO2, labeled CO2 in breath confirms infection

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8
Q

What is the recommended treatment for peptic ulcers?

A 
Triple therapy regimen:
- Proton pump inhibitor (reduces HCl production)
- One pair of antibiotics - 
Amoxicillin and clarithromycin
OR
Metronidazole and clarithromycin
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9
Q

What is a gastrinoma?

A

A gastrin secreting tumour of the pancreas or duodenum that promotes gastric acid production

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10
Q

How is a gastrinoma diagnosed?

A

Fasting serum gastrin (FSG) levels - elevated

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11
Q

What is the treatment for a gastrinoma?

A

Surgery or proton-pump inhibitors

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12
Q

What is oral tolerance?

A

Suppression of immune response against antigens that have previously been eaten as they are seen as harmless

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13
Q

What role does the small intestine have in oral tolerance?

A

It must tolerate ingested food and microbiota, and recognise and control potential pathogens

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14
Q

What is Coeliac disease (CD)?

A

No oral tolerance to gluten

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15
Q

What is gluten?

A

Substance found in endosperm of wheat grains

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16
Q

What is the composition of gluten?

A

Composed of two proteins: gliadin and glutenin

17
Q

What are the three major diseases caused by wheat?

A

Coeliac disease
Non-Coeliac gluten sensitivity
Wheat allergy

18
Q

What is the difference between Coeliac disease and other conditions caused by wheat in terms of disease mechanism?

A

CD - autoimmune reaction causes oral intolerance of gluten

Others - hypersensitivity reaction mediated by IgE mechanism

19
Q

Why is there an increased incidence of Coeliac disease (CD)?

4

A

Greater awareness, testing frequency, gluten exposure, and due to population’s underlying genetics

20
Q

What are the four major symptoms of coeliac disease?

A

Malabsorption (weight loss)
Diarrhoea
Steatorrhea (fat secretion)
Abdominal distention

21
Q

What is dermatitis herpetiformis?

What GI condition is this sometimes seen in?

A

Small groups of blisters on red plaques on knees, elbows, forearms and buttocks; can burst making them itch and sting

Coeliac disease

22
Q

What biological sex has a higher risk of developing coeliac disease? How much higher?

A

Females (XX) - 1.5-2 times higher risk

23
Q

What conditions can a first degree relative have that puts someone at higher risk of coeliac disease?
(4)

A

Autoimmune diseases (T1 diabetes, Hashimoto’s thyroiditis etc.)
Down’s syndrome
Turner’s syndrome
IgA deficiency

24
Q

What has been identified in coeliac disease that makes it unique among autoimmune diseases?
(3)

A

Environmental trigger - gluten
Genetic contribution needed for disease to occur - HLA-DQ2 or HLA-DQ8 haplotype
Autoantibodies - against transglutaminase in 95% of patients

25
Q

What is the association between HLA and coeliac disease?

What other disease has these associations?

A

Most patients with coeliac disease have HLA-DQ2 haplotype and the rest have HLA-DQ8

T1 diabetes is associated with the same DQ molecules

26
Q

What does tTG stand for? What is its relation to coeliac disease?

A

Tissue transglutaminase - body creates autoantibodies (IgA) against this enzyme

27
Q

What effect does tissue transglutaminase (tTG) have on gluten?

A

Gives it a more negative charge - HLA-DQ2 and DWQ8 preferentially bind negatively charged peptides, giving more stable binding

28
Q

Give three signs and symptoms that could call for screening the individual for coeliac disease

A

Chronic diarrhoea, gastrointestinal symptoms (e.g. vomiting, nausea), abdominal pain, sudden weight loss, fatigue, anaemia, faltering growth in children

29
Q

What should be done by the patient before serological testing for coeliac disease?

A

Eat gluten in at least one meal per day for 6 weeks

In children, only test after being exposed to gluten

30
Q

When should a patient with possible coeliac disease stop eating gluten?

A

Only after diagnosis is confirmed by biopsy

31
Q

What serological tests can be carried out to screen for coeliac disease?

What is the preferred test?

A 
Tissue transglutaminase (tTG)
Endomysial antibody (EMA)

tTG is prefered

32
Q

What is endomysial antibody (EMA) and its relation to coeliac disease?

A

Anti-EMA is produced in response to muscle damage from intestinal lining (seen in coeliac disease)

33
Q

What is test is required to diagnose coeliac disease?

A

Biopsy and histological test

34
Q

What is seen in histological examination of a biopsy obtained from someone with coeliac disease?
(4)

A

Atrophied villi
Enlarged crypts
Infiltrated lymphoid cells
Degeneration of surface epithelium

35
Q

What is the cause of the gastrointestinal symptoms of coeliac disease?

A

Intestinal villi - can’t function efficiently due to reduced surface area etc.

36
Q

What system is used to stage coeliac disease?

Why is a grading system needed?

A

MARSH system

Symptoms can be variable with some patients only displaying increased infiltrated lymphocytes

37
Q

What is the MARSH grading system used for?

How many stages are there?

A

Grading coeliac disease

5 grades - 1, 2, 3a, 3b, and 3c

38
Q

What is the treatment for coeliac disease?

A

Gluten free diet

39
Q

How is the treatment of coeliac disease monitored?

A

Regular serological testing of tissue transglutaminase (tTG) - determines effectiveness of therapy and compliance to diet

Introduction to Clinical Biochemistry (11 decks)

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