Malabsorption Flashcards
What disorders of the small intestine cause malabsorption?
Coeliac Dermatitis herpetiformis Tropical Sprue Bacterial overgrowth Intestinal resection Whipple's disease Radiation enteropathy Parasite infection
What is coeliac disease?
A condition where there is inflammation of the mucosa of the upper small bowel that improves when gluten is taken out of the diet but relapses when it is reintroduced
Which cereals are entirely made of gluten?
Wheat
Barley
Rye
What are prolamins?
Damaging factors that are resistant to digestion and trigger immune responses
In coeliac disease does mucosal damage decrease towards the duodenum or ileum?
Ileum
What are some symptoms of coeliac disease?
Tiredness Malaise Diarrhoea Steatorrhoea Abdominal pain Weight loss
How is coeliac disease diagnosed (in all but clear cut cases)?
Small bowel biopsy
Other than small bowel biopsy, what else is sufficient to diagnose coeliac disease?
Serology - tissue transglutamase
What are the histological features of coeliac disease?
Villous atrophy
Crypt hyperplasia
What are the indications for serological testing for coeliac disease?
Persistent diarrhoea Folate or iron deficiency Unexplained abnormal LFTs Family history of coeliac disease Associated autoimmune disease
What antibodies do standard serological tests use for coeliac disease?
IgA
Why might haematology be done for coeliac disease?
To check for anaemia and folate deficiency
Why might biochemistry be done for coeliac disease?
In severe cases there may be osteomalacia or hypoalbuminaemia
What imaging might be done for coeliac disease?
Small bowel barium follow through
or MRI
Why might imaging be done for coeliac disease?
Mainly when a complication such as lymphoma is suspected
Why might bone densitometry be done for coeliac disease?
There is a risk of osteoporosis
Why might a capsule endoscopy be done for coeliac disease?
To look for gut abnormalities when complication is suspected
What may initially be needed in coeliac disease?
Replacement vitamins
What is the management for coeliac disease?
Gluten free diet for life
What is dermatitis herpetiformis?
A blistering, sub-epidermal eruption of the skin associated with gluten-sensitive enteropathy
Is dermatitis herpetiformis common?
No
What is the management for dermatitis herpetiformis?
Dapsone for the skin
Gluten free diet
What is non-coeliac gluten intolerance?
Patients who are sensitive to gluten but coeliac serology is negative and biopsies are normal
What is tropical sprue?
Severe malabsorption accompanied by diarrhoea and malnutrition
What are the symptoms of tropical sprue?
Diarrhoea
Abdominal distension
Weight loss
Anorexia
How long after leaving the tropics can tropical sprue present?
Can be weeks or many years
How is tropical sprue managed?
Most see improvement after leaving the sprue area and taking folic acid
Also may require and antibiotic (usually tetracycline)
What is bacterial overgrowth usually found in association with?
Structural abnormality of the small intestine such as stricture or diverticulum
What are the clinical features of bacterial overgrowth?
Diarrhoea
Steatorrhoea
What causes steatorrhoea?
Deficiency in unconjugated bile salts
How is bacterial overgrowth diagnosed?
Hydrogen breath test
What is classed as small bowel syndrome?
When less than 1m of continuous small bowel remains
Resection of which is better tolerated, jejunum or ileum?
Jejunum
After ileal resection, which substances tend to be deficient?
Bile salts
Vitamin B12
Why might diarrhoea occur after ileal resection?
The mechanism where oligopeptides that reach the ileum without being absorbed delay gastric emptying to allow more absorption is lost.
Less absorption of fluids leads to diarrhoea
What can happen after ileal resection?
Bile salt induced diarrhoea
Steatorrhoea and gallstone formation
Oxaluria and oxalate stones
B12 deficiency
Why might steatorrhoea and gallstone formation happen after ileal resection?
Decreased bile salt absorption means less bile reaching the gallbladder, causing lithygenic bile and gallstone formation
What investigations might be done in ileal resection?
Imaging of small bowel
Measurement of B12
Bile salt retention test (SeHCAT)
Hydrogen breath test
What might jejunal resection lead to?
Gastric hypersecretion
In which resection might adaptation take place that increases absorption?
Jejunal
What can intestinal failure result from?
Obstruction Dysmotility Surgical resection Congenital defect Disease associated loss of absorption
What is short bowel syndrome characterised by?
Inability to maintain protein-energy, fluid, electrolyte or micronutrient balance
When does short bowel syndrome most commonly occur?
Following resection for CD
Mesenteric vessel occlusion
Radiation enteritis
Trauma
What are the two possible situations that can occur in short bowel syndrome?
Shortened small intestine ending at a terminal small bowel stoma
Shortened small intestine in continuity with the colon
What is the major problem when the small intestine ends at a terminal small bowel stoma?
Sodium and fluid depletion
What is Whipple’s disease?
A rare infectious bacterial disease
What organism is Whipple’s disease caused by?
Troptheryma whipplei
Who are the majority of Whipple’s patients?
Males, usually white and middle aged
What are the symptoms of Whipple’s disease?
Arthritis and arthralgia, progressing over years to: Weight loss Diarrhoea Abdominal pain Fever Peripheral lymphadenopathy
What do blood tests show in Whipple’s disease?
Chronic inflammation
Malabsorption
How is diagnosis of Whipple’s made?
Small bowel biopsy
How can T. Whipplei antibodies be identified?
Immunochemistry
How is T. whipplei managed?
Antibiotics that cross the blood brain barrier
Trimethoprim or sulfamethoxazole
What are the chronic affects of radiation?
Muscle fibre atrophy
Ulcerative changes due to ischaemia
Obstruction due to radiation induced fibrotic structures
What areas are most commonly affected by radiation emesis?
Ileum
Rectum
What symptoms may occur during irradiation?
Nausea and vomiting
Diarrhoea
Abdominal pain
What does acute radiation damage cause?
Radiation proctitis with diarrhoea and tenesmus, with or without blood
What are the features of giardia infection?
Diarrhoea
Malabsorption with steatorrhoea
What is the feature of cryptosporidiosis infection?
Malabsorption
