Small Intestine Disorders Flashcards
Explain how the small intestine fulfills a barrier function?
- As a physical barrier
- Also by immune sampling. It takes up bacteria of the gut into peyer’s patches where they are broken down and their antigens studied. In this way it monitors the presence of pathogens and trains the immune system against them
Whats an advantage of a bigger intestine?
You can afford to lose more to surgery without losing function
Why does the small intestine have a smaller bacterial population than elsewhere in the gut?
It has a very toxic environment:
- Digestive enzymes
- Bile Salts
- Presence of IgA
Where is most water absorbed in the gut?
The colon but water absorption begins in the ileum
What enzymes break down fat in the small intestine?
Pancreatic Lipase
What breaks down carbs at the small intestine?
Pancreatic Amylase
Disaccharides are further broken down to monosaccharides at the brush border by disaccharidases (Sucrase, Lactase & maltase)
What are the general symptoms of malabsorption?
Weight loss - Low or falling BMI - Increased Appetite
Steatorrhea
What are the characteristics of steatorrhea?
Caused by Fat Malabsorption leading to high fat content in stool.
- Less dense and floats
- Pale
- Foul smelling
- May leave an oily mark
You can become deficient in all of the below due to malabsorption disorders. What are the signs of their deficiencies?
- Iron/B12/Folate?
- Ca/Mg/VitaminD?
- Vitamin A?
- Vitamin K?
- Vitamin B Complex?
- Vitamin C?
Iron/B12/Folate - Anaemia
Ca/Mg/VitD - Tetany & Osteomalacia
Vitamin A - Night Blindness
Vitamin K - Raised Prothrombin time
Vitamin B Complex
- B1 (thiamine) = dementia
- B3 (Niacin) = Dermatitis & Heart Failure
Vitamin C - Scurvy
List some of the more common small intestinal disorders causing malabsorption?
- Coeliac Disease
- Crohn’s Disease (Variant of IBD)
- Systemic Sclerosis
- Infections
- Chronic Pancreatitis
- CF
This is by no means all
Clubbing & Aphthous ulcerations are a sign of what small intestinal disorders?
Coeliac & Crohn’s
What is dermatitis herpetiformis and what is it a manifestation of?
A cutaneous manifestation of Coeliac Disease.
Blistering & Intense itching on the scalp, shoulders, elbows and kness.
Caused by IgA deposits in the skin
What categories do we divide small intestinal investigations into?
Structural (Many)
Functional (Few)
Name some structural small intestine investigations?
Endoscopy & Biopsy Barium Study CT MRI or Capsule Enterography White cell scan
How does a white cell scan work?
Take blood
- Filter out White cells
- Tag with radioactive tracer
- Inject back in 2-3 hours later
- White cells gather at place of inflammation or infection
Name an explain one functional small intestinal investigation
H2 Breath Test!
Detects lactulose or glucose substrate for bacterial overgrowth.
(You can also culture duodenal fluid)
How common is coeliac disease?
1-2% of the population
What are the symptoms of coeliac disease?
General
- Weight loss
- Steatorrhea/Diarrhoea
- Clubbing
- Fall in BMI
Abdominal bloating, cramps and excessive malodorous flatus are also common.
Also possible is dermatitis herpetiformis
Any signs of vitamin deficiencies e.g. anaemia or osteoporosis
What tests are there for ceoliac disease?
- Start with Serology
- If in doubt -> Distal Duodenal Biopsy
- Can also check HLA status
How do we test for coeliac disease serologically?
Test for anti tissue-transglutaminase (anti-TTG) IgA antibodies .
2-3% of coeliacs dont make the IgA variant so can test for IgG version.
What would show up in a distal duodenal biopsy for coeliac disease?
Flattened villi: Partial/subtotal/total villlous atrophy due to inflammation causing early death of enterocytes
Longer crypts: Crypt hyperplasia
Increased intraepithelial lymphocytes
What is “HLA status” (Human Leukocyte antigen)?
A gene test
97% of coeliacs are either HLADQ2 or DQ8 +ve
However so are 30% of non-coeliacs
Use it for exclusion, if -ve very unlikely to be Coeliac.
Explain the pathophysiology of Coeliac disease?
Sensitivity to gluten. which is a fraction of gliadin found in wheat.
Gluten -> Inflammation via tissue anti-transglutaminase antibodies -> Villous atrophy & increased intra-epithelial lymphocytes
How do we treat celiac disease?
Refer to a proper registered dietitian to help them withdraw gluten from their diet for life
