MALABSORPTION Flashcards
What symptom to people almost always get in malabsorption?
Diarrhoea
What do stools look like in fat malabsorption? What colour will they be if bile is absent? Explain why
Steatorrhea
Pale if bile absent due to lack of bilirubin
Carbohydrate malabsorption will result in what type of diarrhoea? Explain why
Watery diarrhoea: unable to absorb sugar molecules, which have osmotic effect
How does gluten initiate a T-cell response in coeliac disease?
Gluten is made up of gliadin and glutenin
Gliadin is the pathogenic component of gluten
⇒ to become pathogenic gliadin has to be deamidated by tissue transglutaminase (tTG). This form of gliadin is consumed by antigen-presenting cells and presented to T cells, initiating a type IV hypersensitivity response
What are the three classic histological changes seen in coeliac disease?
- Blunting of villi
- Crypt hyperplasia
- Lymphocytes in lamina propria
Duodenum most commonly affected
Which two antibody tests have the highest accuracy for screening coeliac disease?
what is an exception to this?
- IgA endomysial
- IgA tTG
Total IgA antibodies should always be checked initially → in people who are IgA deficient, should check IgG of the above antibodies instead
Why do people with coeliac disease develop iron deficiency anaemia?
Iron is absorbed in the duodenum
What should you consider in a patient with coeliac disease who is adherence to a gluten-free diet but develops worsening symptoms?
Small-bowel malignancy: very rare condition but coeliac disease is one risk factor
Patient with coeliac disease presents with the following skin complaints. What is this and what is it called by?
how is it treated?
Dermatitis herpetiformis → herpes like lesions on skin
Skin condition associated with coeliac disease caused by IgA Ab deposition in dermal papillae
Resolves with a gluten-free diet
57 yo male develops attack of acute diarrhoea, fever and malaise following trip to Caribbean. After a variable period, he settles into chronic phase of diarrhoea, steatorrhoea, weight loss, anorexia, malaise, and folate deficiency.
On small bowel biopsy there is blunting of villi and presence of inflammatory cells. What is the diagnosis and how would you treat? How do you differentiate from another condition that causes bloating of the villi?
Tropical sprue: treat with antibiotics + folate
Differentiated from coeliac disease by the fact that entire small-bowel is affected
What causes lactose intolerance? What is the main symptom? What would you see on histology?
- Absence of or abnormal lactase enzyme meaning that lactose is not broken down in small-bowel to glucose and galactose. Lactose remains in small-bowel → osmotic
- High volume, watery diarrhoea, cramps, flatulence
- Normal histology
How do you diagnose lactose intolerance? Two points
- Often clear from history
- Lactose breath hydrogen test: patient ingest lactose, if undigested, bacteria will ferment lactose and produce hydrogen which is then measured
How can cystic fibrosis cause steatorrhea?
Pancreatic obstruction causing fat malabsorption
Unlike the colon, the small intestine is nearly sterile. What happens if there is significant bacterial overgrowth? What is the main cause?
Small intestine bacterial overgrowth
- Can cause excessive fermentation, inflammation and malabsorption
- Bloating, flatulence, abdominal discomfort → chronic diarrhoea, vitamin deficiencies
♦ Main cause is dysmotility through small intestine
