pathology of malabsorption Flashcards
what are the signs of malabsorption?
weight loss
pale stools or steatorrhoea
anaemia
what should be established first before thinking about a pathological reason for malabsorption?
check that the pt’s diet is balanced
what part of the intestine is where cells divide to form new cells?
the crypts
is it normal for their to be lymphocytes in the villi of the intestine?
yes, small numbers are fine as these fight off infection in the food
what are the causes of malabsorption?
insufficient intake defective intraluminal digestion insufficient absorptive area lack of digestive enzymes defective epithelial transport lymphatic obstruction
give reasons for defective intraluminal digestion
pancreatic insufficiency: pancreatitis and CF both mean that pancreatic enzymes cannot be produced
defective bile secretion - due to biliary obstruction and ileal resection; means less fat emulsion and decreased bile salt uptake respectively
bacterial overgrowth - bacteria use up the nutrients in the food, so they are not absorbed
what conditions cause insufficient absorptive area?
gluten sensitive enteropathy ie Coeliac
Crohn’s disease
extensive surface parasitisation
How does gluten sensitive enteropathy look on histology?
short villi and larger crypts ie crypt hyperplasia
increased number of intraepithelial lymphocytes
what is coeliac disease?
allergic hypersensitivity reaction to gluten from wheat
explain the pathophysiology behind Coeliac disease
gliadin protein is absorbed from gluten
the gliadin protein binds to APCs
APCs present gliadin to toxic T cells
Toxic T cells cause epithelial cell injury by release of chemicals
transglutaminase Abs are produced which destroy the villi
which part of the bowel does Crohn’s disease primarily affect?
small intestine
Give an example of a parasite that causes extensive surface parasitisation in the intestine?
Giardia lamblia
What happens in extensive surface parasitisation?
parasites prevent the absorption of food
What are the reasons that sb might have a small intestine resection or bypass?
morbid obesity
Crohn’s disease
infarcted small bowel
What are some lack of enzyme diseases that can cause malabsoption?
disaccharidase deficiency (lactose intolerance) bacterial overgrowth damages the brush border, so affects the release of enzymes
