Small Intestine Flashcards
What are the 3 mechanisms of malabsorption
Structural disorder
Mucosal disorder
Abnormal luminal digestion
What are the general clinical features of malabsorption
Malaise Anorexia abdominal bloating diarrhoea weight loos
What are some specific clinical features of malabsorption
Steatorrhoea (fat malabsorption)
Oedema ascites (protein malabsorption)
Skin rash (Zn or Vit B malabsorption)
Cheilitis, glossitis (vitamin B malabsorption)
Neuropathy, psychological effects (vit B12 malabsorption)
Night blindness (vit A malabsorption)
Bruising (vit K or vit C malabsorption)
Bone pain, myopathy, oesteoporosis (vit D malabsorption)
What are the 3 aims of investigating malabsorption
To establish the condition
To identify the site of abnormality
To identify the severity
What is short bowel syndrome
This is typically when there is
When does short bowel syndrome occur
When there is insufficient functioning small intestine to allow normal digestion and absorption
What are some causes of short bowel syndrome (intestinal failure)
Extensive surgery Crohn's disease Mesenteric ischaemia Radiation damage Volvulus Congenital abnormalities in children
What is the short term management of SBS
Correct malnutrition
Reduce gut secretions (PPI, codeine, loperamide)
What is the long term management of SBS
Monitor nutrition and ensure adequate calorie intake
Monitor hydration status
Replace vitamins and mineral
Reduce gut secretions
Treat small intestinal bacterial overgrowth
Cholecystectomy if gallstones develop
Small bowel transplantation
What is Ceoliac disease
An immune mediated disorder resulting in small intestinal villous atrophy which resolves on gluten withdrawal from the diet
What is the main toxic antigenic component of fluten
Alpha - gliadin
What does the protein in gluten cause
A T cell mediated inflammatory response of the small bowel
What is the prevalence of Coeliac disease in the UK
1:200
What are clinical features of Coeliac disease
Failure to thrive at weaning time (infants) Abdominal pain / bloating Lethargy Anaemia Diarrhoea or constipation
What is Coeliac disease linked to
HLA-DQ2
What is coeliac disease often linked to
Other autoimmune diseases such as dematitis herpetiformis, insulin dependent diabetes, thyroid disease, primary biliary cirrhosis
What are the investigations to confirm the fiagnosis
Duodenal biopsy is GOLD STANDARD
What would be seen on a duodenum biopsy in someone with Coeliac disease
Villous atrophy
Crypt hyperplasia
Intraepithelial lymphocytosis
What antibody needs to be tested for in Coeliac disease
IgA antibodies to Tissue transglutaminase (TTG)
Why might a patient get a false negative result for IgA
IgA deficiency
What should be tested when investigating the consequences of Coeliac disease
FBC and blood film
Haematinincs
Clotting screen
Bone investigation
What is the management for Coeliac Disease
Life long gluten-free diet to prevent the ongoing antigen provocation of the inflammatory response
Correct deificencies
Aggressive management of any bone disease
What is tropical sprue
A rare condition associated with small intestine villous atrophy and is thought to be post-infectious.
Who does tropical spruce normally affect
Residents of tropical countries (not travellers)
What are 2 common symptoms of tropical sprue
Diarrhoea and abdominal distension
What is the treatment for Tropical sprue
Longterm tetracycline and folic acid
What 3 things does colonisation of the small intestine by colonic flora result in
Deconjugating bile salts (diarrhoea)
Metabolising vitamin B12 (anaemia)
Metabolising carbohydrate (resulting in calorie malnutrition and halitosis)
What 2 investigations are carried out for the condition of small intestinal bacterial overgrowth?
Jejunal aspirate
Hydrogen breath test after ingesting glucose or lactulose
How is the cause of small intestinal bacterial overgrowth investigated
Small bowel radiology (identifies structural or communication abnormalities )
What is a complication of Small intestinal bacterial overgrowth investigated
Low B12 and normal folate
What 3 things are required in the management of small intestinal bacterial overgrowth
Antibiotics directed towards colonic flora
Replace vitamin B12
Definiteive treatment if poosible - surgery or prokinetics
What is bile acid malabsorption characterised by
Postprandial diarrhoea due to osmotic effect of bile salts in the colon or steatorrhoea
If bile acid malabsorption is a secondary abnormality, what is it most commonly due to
Crohn’s disease
ileal resection
intestinal failure
What is teh treatment for bile acid malabsorption
Cholestyramine - a bile acid sequestrant
What is Whipple’s disease
A rare disease characterised by malabsorption, finger clubbing, fevers, skin pigmentation, seronegative large-joint arthropathy
How is the diagnosis of Whipple’s disease established
By identifying foamy fmacrophagses which stain positive with periodic acid-Schniff on jejunal biopsy
What is the treatment for Whipple’s disease
Cotrimoxazole or tetracycline for 1 year
What is protein-losing enteropathy
Gut loss of protein sufficient to reduce serum albumin
How common are small intestine tumours
Very rare - account for
What are the 2 important types of small intestine tumours
Carcinoid and lymphoma
Describe carcinoid tumours
Slow growing and arise from the appendix, small intestine or rectum
When does carcinoid syndrome occur
Only if the tumour metastasises
What is carcinoid syndrome caused by
Systemic release of serotonn, prostaglandins and bradykinins
How are carcinoid tumours diagnosed
By measuring urinary 5-HIAA
What is the treatment for carcinoid tumours
Surgical resection
What are 3 main presentations of carcinoid syndrome
Wheezing
Flushing
Diarrhoea
What is the diagnostic test for lymphoma
Abdominal CT
What is the treatment of choice for lymphoma
Surgical resection
What is immunoproliferative small intestinal disease
A rare condition also known as alpha heavy chain disease
Who does immunoproliferative small intestinal disease normally affect
Mediterranean and Arab races
How do patients with immunoproliferative small intestinal disease typically present
With diarrhoea
malabsorption
clubbing
weight loss
What shows the alpha heavy chains in immunoproliferative small intestinal disease
Serum electrophoresis
What is the treatment for immunoproliferative small intestinal disease
Long term antibiotics
Only some need chemotherapy
What is more common: single polyp or multiple polyps
Multiple polyps
What are the 3 types of multiple polyps
Nodular lymphoid hyperplasia
Hamartomas
Andeomatous
What is chronic intestinal pseudo-obstruction
Refers to a dpectrum of rare disorders characterised by the signs and symptoms of intestinal obstruction in the absence of true obstruction
What is required to determine the diagnosis of chronic intestinal pseudoobstruction
Radiological demonstation of a dilated proximal small bowel
What is Meckel’s diverticulum
The commonest congenital gut abnormality resulting from failure to close the vitelline duct
If a patient is symptomatic with Meckel’s diverticulum, at what age would they present?
Before the age of 2
Males are twice as likely to be affected. True or False
True
What are the classic symptoms of Meckel’s diverticulum
Painless melaena with intestinal obstruction or intussusception being rare
How is Meckel’s diverticulum diagnosed
Using a Meckel’s scan - injecting a radioisotope which is taken up by ectopic parietal cells
Who is most likely to have hypolactasia
Africans and Asians
What might secondary causes of lactase deficiency result in
Osmotic diarrhoea, abdominal pain
borborygmi after eating milk products
Flatulence
How is diagnosis of lactase deficiency made
Using a lactose substrate hydrogen breath test
What is the treatment for lactase deficiency
Minimising milk products
In food allergy, what type of hypersensitivity reaction occurs
Type 1
What is the treatment for food allergy
Dietary avoidance
