Malabsorption Syndrome Flashcards

1
Q

How common is Coeliac disease?

A

Affects ~ 1% of UK population

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2
Q

What is Coeliac disease?

A
  • intolerance to gluten
  • in particular, gliadin, the alcohol-free fraction of gluten, is the disease-producing component
  • gluten is found in wheat, barley and rye
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3
Q

What is the brief pathogenesis of coeliac disease?

A
  • not fully understood
  • thought that gliadin triggers inappropriate activation
  • of intestinal T cells
  • in genetically susceptible individuals (ppl w/ HLA-DQ2 and HLA-DQ8 haplotypes)
  • resulting in damage to epithelial cells
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4
Q

Now explain in more detail what happens in patients with coeliac when gluten is digested in comparison to a healthy individual?

A
  • gluten digested by luminal and brush-border enzymes in small intestine
  • into aino acids + peptides, incl 33AA gliadin peptide
  • gliadin is deamidated in mucosa by tissue transglutaminases (tTG)
  • in those w/ HLA-DQ2 and HLA-DQ8 haplotypes, deamidated gliadin closely fits the MHC II grooves
  • gliadin presented to T helper cells by antigen presenting cells
  • initiates a Th2-predominant immune response
  • generates cytotoxic T cells against gliadin
  • cytotoxic T cells migrate into intestinal epithelium, visible on biopsy as intraepithelial lymphocytes
  • the T cells damage + destroy epithelial cells resulting in progressive villous atrophy
  • as a result, crypts become hyperplastic to compensate for cell loss
  • loss of normal small bowel fxn -> malabsorption
  • also a humoral immune response w/ generation of antigliadin, antiendoymysial and antiTTG antibodies - useful antibodies diagnostically
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5
Q

What is the clinical presentation of coeliac disease?

A
  • at any age, most commonly in childhood or middle age
  • symptoms of malabsorption (diarrhoea, steatorrhoea, weight loss, lethargy, bloating, abdo pain)
  • non-specific symptoms: eg. anaemia (usually iron def), irritable bowel syndrome-like symptoms, altered bowel habit, abdo pain
  • in children, coeliac disease is an important cause of failure to thrive and delayed puberty
  • an intensely itchy and blistering rash over elbows + buttocks - dermatitis herpetiformis
  • some pts are asymptomatic and diagnosis is discovered incidentally
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6
Q

How is coeliac disease diagnosed?

A
  • history and examination
  • gluten-containing diet better to be consumed during diagnostic process
  • serology tests: total IgA and IgA tissue transglutaminase antibodies are currently the preferred first line test (owing to its high sensitivity and negative predictive value)
  • IgA anti-endomysial (EMA) antibodies can be used if IgA tTG is weakly positive
  • gold standard ix: endoscopy and duodenal biopsy
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7
Q

What does tissue biopsy for positive coeliac show?

A
  • villous atrophy
  • crypt hyperplasia
  • prominent intraepithelial lymphocytes

Generally agreed that duodenal biopsy should be performed on all adult patients to confirm the diagnosis

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8
Q

What is the treatment for coeliac?

A
  • Life-long gluten-free diet
  • Those with coeliac disease (+ fam members, carers) should be given sources of info on the disease, including a national and local specialist coeliac groups and dietiticans with a specialist knowledge of coeliac disease
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9
Q

What are complications of coeliac disease?

A
  • Malabsorption (-> anaemia + deficiencies)
  • Osteopenia/osteoporosis
  • Dermatitis herpetiformis
  • Lymphoma
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10
Q

Why do patients with coeliac develop osteopenia/osteoporosis? How can this be investigated and treated?

A
  • most pts w/ coeliac disease are osteopenic (reduced bone density)
  • bc they fail to reach their peak bone mass during young adult life
  • due to malabsorption of calcium
  • reduction in bone density is usually mild, most pts are only osteopenic
  • however, some are actually osteoporotic w/ associated risk of fracture
  • at dx, pts given lifestyle advice + basline DEXA scan to assess bone mineral density
  • pts should maintian adequate calcium and vit D intake
  • a gluten-free diet should prevent further bone loss and may improve bone density
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11
Q

Why do coeliac patients develop dermatitis herpetiformis?

A
  • intensely itchy chronic blistering skin condition
  • typically occurs symmetrically on extensor surfaces (buttocks, back of neck, knees, elbows etc)
  • it’s not related to herpes virus
  • rather, associated w/ coeliac disease although exact mechanism not fully understood
  • may be due to autoantibodies to epidermal transglutaminase
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