Malabsorption and Small Intestinal Disease Flashcards
(42 cards)
What are the functions of the small intestine?
Digestion: Breaking of food into its components
Absorption: Passage of nutrients into the body
Endocrine and neuronal control functions: Controlling the flow of material from the stomach to the colon
Barrier functions: Maintaining a barrier against pathogens
How does the small intestine maintain a barrier against pathogens?
Immune sampling
Monitoring the presence of pathogens
Translocation of Bacteria
Gut Associated Lymphoid Tissue (GALT)
What is Gut Associated Lymphoid Tissue?
The intestines contain the largest accumulation of lymphoid tissues in the body in the form of lymphoid aggregates in Peyer’s patches and in the lamina propria.
This all makes up the GALT
Why must the GALT be careful in its battle against pathogens?
It must react to the bad pathogens (e.g. typhoid) but it can’t over react and attack the food we eat.
How long is the small intestine and what is the limit of this length for it still to function?
Average length 2.5-4.5m
(achieved by 11 yrs)
Can still function effectively with only 1.5m
How does the small intestine maintain its low bacterial population?
Creates a toxic environment:
- Digestive enzymes
- Bile salts
- Presence of IgA etc
Motility:
- Constantly moving stuff on and cleaning itself
- Motility problems can lead to bacterial growth
Despite the small intestines fantastic ability to remain relatively sterile what organism can live?
Giardia Lamblia
- Unicellular parasite
- Contaminated water
- Responds to Metronidazole
- Hypogammaglobulinaemia
- Actually needs bile to survive
Why in digestion does the final hydrolysis usually occur at the brush border?
Absorption can immediately follow the full digestion to prevent osmotic shifts.
What are the symptoms of small intestinal disease?
Weight loss
Increase Appetite
Steatorrhoea
What is steatorrhoea?
A form of diarrhoea
Fat malabsorption High fat content in stool Stool less dense and floats Pale Foul smelling may leave an oily mark
What are the signs of small intestinal disease?
Signs of weight loss
Low or falling BMI
What are the most common nutrients to be malabsorbed?
Iron, B12 and Folate
What vitamins could you see a deficiency in with someone who presents with steatorrhoea?
Vitamin D (Tetany, Osteomalacia) Vitamin A (Night blindness) Vitamin K (Raised PTR, problems with haemodynamics)
What signs might you see in someone with a Thiamine (Vit B2) deficiency and how much should you give to replace this if they are ill?
Loss of short term memory
Dementia
It isn’t known how much thiamine you require when you are ill but it is a lot.
If you are in any doubt about a deficiency replace
What is the other name of Vitamin B3?
Niacin
Deficiency can cause dermatitis and unexplained heart failure
What can a lack of vitamin C cause?
Scurvy
Name 3 non-specific Signs of specific illness that affects the small intestine
Clubbing: Coeliac Disease, Crohn’s
Scleroderma: Systemic Sclerosis
Aphthous Ulceration: Coeliac, Crohn’s
What is scleroderma?
Autoimmune disease causing hardening of the skin.
In the more severe form it affects internal organs = Systemic sclerosis
what is aphthous ulceration?
Repeated formation of benign and non-contagious mouth ulcers
What is Dermatitis Herpetiformis?
Cutaneous manifestation of coeliac disease
Blistering
Intensely Itchy
Scalp, Shoulders, Elbows, Knees
IgA deposit in skin
Very unusual but VERY itchy
What are the tests you can use to assess the structure of the small intestine?
Small bowel biopsy Small bowel study White cell scan CT scan MRI enterography Capsule enterography
How can you test for bacterial overgrowth in the small intestine?
H2 Breath Test:
- Lactulose or Glucose substrate
- Broken down to form marked hydrogen
- Not terribly accurate
culture a duodenal or jejunal aspirate
When carrying out a test of an antibody subset what must you do in addition?
e.g. when testing for Anti TTG
Do a test to check if they can produce the antibody in the first place
E.g. Anti Tissue Transglutaminase (Anti-TTG) IgA
-Afterwards do a test for IgA to see if the person can actually produce it (no adverse effect if not)
How do you confirm Coeliac disease?
Distal Duodenal Biopsy.
-Looking for Villous atrophy
Serology
- Anti endomysial IgA
- Anti Tissue Transglutaminase
- –Both 95% specific and sensitive
