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Life Maintenance > Clinical approach to diarrhoea > Flashcards

Clinical approach to diarrhoea Flashcards

1
Q

What is diarrhoea?

A

excessively frequent and loose bowel movements

>300g/24 hours

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2
Q

What is malabsorption?

A

imperfect absorption of food material by the small intestine

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3
Q

What are the main types of diarrhoea?

A

Osmotic
Exudative
Secretory
Motility

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4
Q

What is osmotic diarrhoea?

A

non-absorbable solute

  • deficiency in digestive enzymes
  • lactulose
  • magnesium salts
  • sorbitol
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5
Q

What is exudative diarrhoea?

A

intestinal mucosal damage

  • infections
  • IBD
  • Coeliac
  • irradiation
  • ischaemia
  • colon cancer
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6
Q

What is secretory diarrhoea?

A

impaired electrolyte transport

  • bacterial endotoxins
  • bile salts
  • laxatives
  • hormone producing tumours
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7
Q

What is motility diarrhoea?

A

increased transit through GI tract

  • IBS
  • thyrotoxicosis
  • autonomic neuropathy (DM)
  • drugs
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8
Q

What are the 3 phases of malabsorption?

A
  • luminal phase
  • mucosal phase
  • transport phase
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9
Q

What are the main processes underlying the luminal phase of malabsorption?

A
  • reduced nutrient availability
  • impaired fat solubilisation
  • defective nutrient hydrolysis
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10
Q

What are the main processes underlying the mucosal phase of malabsorption?

A
  • mucosal loss and damage

- enterocyte deficit

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11
Q

What are the main processes underlying the transport phase of malabsorption?

A
  • vascular inflammation/disease

- lymphatic damage/disease

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12
Q

What clues in the history are important to consider for malabsorption?

A
  • time course and severity
  • impact of fasting on Sx
  • volume and consistency of stools
  • floating stools (steatorrhoea)
  • malaena (bloody stools)
  • nocturnal Sx
  • constitutional Sx (anorexia/weight loss, fever, vomiting)
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13
Q

What are causes of diarrhoea that may present in the history?

A

PMHx:
childhood illness
IBS
previous GI surgery

Drugs

SHx/FHx:
foreign travel
dietary factors (intolerances)
ethnicity
contacts with similar Sx
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14
Q

What are some clinical features of malabsorption?

A

angular stomatitis, glossitis (iron/vitamin B12 deficiency)
osteomalacia (vitamin D and Ca deficiency)
Leukonichia (protein deficiency)
Tetany (Ca deficiency)
Bruising (Vitamin K deficiency)
Oedema (protein deficiency)

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15
Q

What are the main investigations ordered for diarrhoea?

A

Bloods
(FBC, ESR, U&E, TFTs, LFTs, CRP, iron studies, coeliac serology, vitamin B12 and folate)

Imaging
(barium/meal swallow study, CT/MRI)

Stool tests
(calprotectin, elastase, M C and S)

Functional studies
(hydrogen breath test - H. pylori, Schilling test)

Endoscopy
(OGD with D2 biopsies, colonoscopy, capsule endoscopy)

Gut hormone profile (Gastrin, glucagon, VIP, PP)

Urinary catecholamines

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16
Q

What is the Schilling test used to investigate?

A

Ordered to identify vitamin B12/cobalamin deficiency

Looks at how well vitamin B12 is absorbed from the GI tract in the patient (examination of stool)

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17
Q

Why are urinary catecholamines (CATU) ordered in diarrhoea?

A

some diseases increase catecholamine production, urinary screening is often coupled with a catecholamine blood test

In adults, urinary catecholamines are used to screen for PHAEOCHROMOCYTOMA

In children, CATU screening is performed to identify NEUROBLASTOMAS

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18
Q

What is irritable bowel syndrome (IBS)?

A 
functional GI disorder
a disorder of gut-brain axis interaction
Sx are usually combos of the following:
- motility disturbance
- visceral hypersensitivity 
- altered mucosal and immune function
- altered gut microbiota
- altered CNS processing
19
Q

What is the demographic for IBS in the western world?

A

~20% of adolescent/adult Westerns have symptoms consistent with IBS

20
Q

What are the Rome IV criteria for IBS Dx?

A

recurrent abdo pain
for at least 1 day/week for last 3 months (on average)
associated with 2 or more of the following:
- related to defecation
- change in frequency of stool
- change in form/appearance of stool

Criteria fulfilled for preceding 3 months with Sx for the preceding 6 months for Dx

21
Q

What are the main methods of management for IBS?

A 
Ix/reassurance 
Diet
Lifestyle advice
Medications (symptom relief)
- Anti-spasmodic (mebeverine, peppermint oil) 
- Altering intestinal transit (Opiates: loperamide, laxatives)
- probiotics
- Antidepressants
22
Q

What is Coeliac disease?

A

inflammatory condition of small intestinal mucosa
mot marked proximally
improves morphologically when gluten is removed from diet

23
Q

What is gluten?

A

breakdown product of wheat protein
Gluten: gliadins (alpha, omega, gamma) and glutenins subcomponents
The specific aa sequence found in gliadin is also found in rye and barley

24
Q

What is the pathogenesis of Coeliac disease?

A

inherited auto-immune condition
HLA-DQ2 genotype (95% association, but not causal as genetic risk is polygenic)
HLA-DQ2 genotype present in 20% of population
likelihood of 1st degree relative having CD is 10-15%
Auto-antibodies:
- anti-gliadin
- anti-reticulin
- anti-endomysial

25
Q

What is the prevalence of Coeliac in the UK?

A

iceberg effect in that only symptomatic CD (with +ve histology) is seen
There are also many other people with asymptomatic CD (positive histology) and latent CD (-ve histology)

26
Q

What are the Sx of Coeliac that present during childhood?

A

failure to thrive/short stature
diarrhoea/steatorrhoea
vomiting (50% of patients)
abdo pain/distension

27
Q

What are the Sx of Coeliac that present in adulthood?

A 
fatigue (80-90%)
anaemia (85%)
diarrhoea/steatorrhoea (75-80%)
weight loss
mouth ulcers 
infertility
28
Q

What are the criteria for Sx of Coeliac in adults?

A

4 intestinal biopsies

i) abnormal mucosa on gluten consumption (histological change may be minimal)
ii) improvement on gluten-free diet (over 3-6 months)

29
Q

How long can it take for mucosal healing to occur after initiation of a gluten-free diet in Coeliac?

A

may take up to 2 year, or could remain incomplete

Sx should improve in 3-6 months of complete restriction of gluten

30
Q

What are the histological markers of Coeliac disease?

A

flattening of cilia on enterocytes
erythema of duodenal mucosa
elongation of intestinal crypts

31
Q

What is the sensitivity and specificity of the IgA anti-endomyosial test?

A

Sensitivity: 85-98%

Specificity: 97-100%

32
Q

What is the sensitivity and specificity of the IgA anti-tTG?

A

Sensitivity: 95-98%

Specificity: 94-95%

33
Q

What is tTG? What is its function?

A

tissue transglutaminase
deamidates the glutamine residues on gliadin
this makes it more immunogenic and increases the binding affinity to MHC class II molecules on T cells
-> stronger adaptive immune response generated

34
Q

What is the sensitivity and specificity of the IgA anti-gliadin?

A

Sensitivity: 75-90%

Specificity: 82-95%

35
Q

What is the sensitivity and specificity of the IgG anti-gliadin?

A

Sensitivity: 69-85%

Specificity: 73-90%

36
Q

What other conditions are associated with coeliac disease?

A 
(other autoimmune conditions)
T1DM
thyrotoxicosis 
IgA deficiency 
Sjogren's disease
osteoporosis 
primary biliary cirrhosis
37
Q

What is Sjogren’s disease?

A

F > M
affects body parts where fluid is produced e.g. tears and saliva
causes dryness in these areas
No cure for disease, treatments are for symptomatic relief

38
Q

What is dermatitis herpetformis?

A

complication present in 2-5% of patients with CD
pr: 1:20,000 in UK
M>F
improved by gluten free diet

Dx: granular IgA at dermo-epidermal junction of unaffected skin

39
Q

What are the treatment options of Coeliac disease?

A

gluten free diet
dietary supplements (Fe, folate, Ca, vitamin B12)
screening for bone abnormalities and hyposplenism
(prophylactic antibiotics may be given for the latter)

40
Q

What are the benefits to a Coeliac sufferer adhering to a gluten-free diet?

A 
improvement of Sx
reduced risk of complications:
- osteoporosis 
- malignancies
- autoimmune diseases
41
Q

What is the follow-up protocol for Coeliac patients?

A 
6 monthly outpatients
repeat small intestinal biopsy after 1st 6 months 
blood tests
Sx assessment
nutritional assessment 
dietary compliance

Close monitoring during pregnancy

42
Q

What factors are important to check when there is a poor response/relapse of Coeliac?

A
  • dietary compliance
  • correct Dx
  • co-incident disease
    (ulcerative jejuna-ileitis, microscopic colitis, malignancy)
43
Q

What types of malignancy are associated complications of Coeliac disease?

A
  • lymphoma
  • small bowel (adeno)carcinoma
  • oesophageal/colonic carcinoma

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