Malabsorption and Small Intestinal Disease Flashcards
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
What is villous atrophy?
Villi of the intestine have shrunk.
Lots of crypts
The life time of the enterocyte in coeliac disease is greatly reduced so that villi can’t actually form
What is Coeliac Disease?
The most common malabsorption disease.
Sensitivity to Gliadin which is a fraction of Gluten.
What foods in Gliadin found?
Gluten is found in Wheat, Rye and Barley.
Absent from rice and maize.
Not found in oats but most oat products are contaminated with wheat
What is the pathology of Coeliac Disease?
Produces and inflammatory response
-This is thought to be via tissue transglutaminase (which can be tested)
Partial or subtotal villous atrophy (may cause iron deficiency also)
Increased intra-epithelial lymphocytes
Gold standard diagnosis is still a distal duodenal biopsy
In addition to Anti Endomysial IgA and Anti TTG what other test can be useful for diagnosing Coeliac in children?
Anti Gliadin
May help in children but not diagnostic in adults
What is the treatment for Coeliac disease and why is it absolutely fucking shit?
Withdraw Gluten
Problem is that:
- Wheat is used widely in commercial food (GOUJONS)
- Diet is life long
GET THAT SON BITCH A DIETITION
Name some of the conditions associated with Coeliac disease
Dermatitis Herpetiformis IDDM Autoimmune thyroid disease Autoimmune hepatitis Primary Biliary cirrhosis Autoimmune gastritis IgA deficiency Downs Syndrome
What is IDDM?
Insulin Dependent Diabetes Mellitus
aka Type 1 diabetes
What are the complications of Coeliac Disease?
Refractory coeliac disease Small bowel lymphoma Oesophageal carcinoma Colon Cancer Small bowel adenocarcinoma
What is refractory Coeliac disease?
Patient doesn’t respond to diet.
Some patients are massively sensitive and so cross contamination is a huge issue
What are the inflammatory causes of malabsorption?
Coeliac Disease
Crohn’s
What are the infective causes of malabsorption?
Tropical sprue
HIV
Giardia Lamblia
Whipples Disease
What is tropical sprue?
- Folate deficiency
- Very like coeliac but will respond to antibiotics
- Keep an eye out for risk areas
What is Whipples disease?
Middle aged men Skin, brain, joints and cardiac effects Weight loss Malabsorption Abdominal pain PAS material villi
Tropheryma whippelii is the causative organism
What are the impaired motility diseases that may cause impaired motility?
Systemic sclerosis
Diabetes
Pseudo obstruction
What are the iatrogenic causes of malabsorption?
Gastric surgery
Short bowel syndrome
Radiation
What are the pancreatic causes of malabsorption?
Chronic pancreatitis
Cystic fibrosis
What are the two important points to pick out of a history when you suspect malabsorption?
Weight loss
Steatorrhoea
