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MD2 Medicine > Diarrhoea and Malabsorption > Flashcards

Diarrhoea and Malabsorption Flashcards

1
Q

How much fluid enters the gastrointestinal tract?

A

9 L

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2
Q

Where and how much fluid is absorbed in the gastrointestinal tract?

A

Small bowel - 7 L

Colon - 1.8 L

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3
Q

On what does absorption of water depend?

A

Absorption of solutes, especially Na

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4
Q

How are carbohydrates digested?

A

Salivary and pancreatic amylases

Brush border enzymes

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5
Q

Ho are proteins digested?

A

HCl
Gastric pepsin
Pancreatic peptidases

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6
Q

How is fat digested?

A

Bile

Pancreatic lipase

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7
Q

What is diarrhoea?

A

Abnormal frequency and liquidity of stool
Can cause excess fluid and electrolyte loss
Stool >200 g/day and >3 movements/day

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8
Q

When is diarrhoea defined as chronic?

A

Persists for >4 weeks

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9
Q

What investigations on faeces could help establish the mechanism or diagnosis for diarrhoea?

A 
Microscopy and culture
Faecal electrolytes and osmolarity
Faecal fat
Faecal elastase
Clostridium difficile toxin
Faecal calprotectin
Faecal laxative screen
Faecal alpha1-antitrypsin
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10
Q

Of what is faecal elastase a marker?

A

Exocrine pancreatic sufficiency

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11
Q

Of what is faecal calprotectin a marker?

A

GI inflammation
Used if
- May have IBD, and can’t have diagnostic colonoscopy
- Not sure if have IBD

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12
Q

What can be included in a faecal laxative screen?

A

Anthroquinones
Bisacodyl
Phenolphthalein

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13
Q

Of what is alpha1-antitrypsin a marker?

A

Protein losing enteropathy

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14
Q

What causes osmotic diarrhoea?

A

Presence of excess unabsorbed substrates in gut lumen

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15
Q

What is a common cause of osmotic diarrhoea?

A

Fermentable carbohydrate (FODMAPs) malabsorption

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16
Q

What is the stool volume in osmotic diarrhoea?

A

Typically <1 L

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17
Q

What is the effect of fasting on osmotic diarrhoea?

A

Stops with fasting

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18
Q

Are there stool leukocytes in osmotic diarrhoea?

A

No

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19
Q

What causes secretory diarrhoea?

A

Active anion secretion from enterocytes

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20
Q

What are the common causes of secretory diarrhoea?

A 
Bacterial toxins
- Cholera
- ETEC
Hormone secreting tumours
- Carcinoid
- Gastrinomas
Laxative abuse
Hyperthyroidism
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21
Q

What is the stool volume in secretory diarrhoea?

A

Usually >1 L

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22
Q

What is the effect of fasting on secretory diarrhoea?

A

Persists during fasting

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23
Q

Are there stool leukocytes in secretory diarrhoea?

A

No

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24
Q

What causes inflammatory diarrhoea?

A

Altered membrane permeability > exudation of

  • Protein
  • Blood
  • Mucus
25
Q

What are the common causes of inflammatory diarrhoea?

A 
Invasive bacteria
- Shigella
- Salmonella
- Campylobacter
- Clostridium difficile
Entamoeba hystolytica
CMV colitis
IBD
26
Q

What is the stool volume in inflammatory diarrhoea?

A

Usually small

27
Q

Are there leukocytes and erythrocytes present in the stool in inflammatory diarrhoea?

A

Yes, increased RBCs and leukocytes

28
Q

What other symptoms can inflammatory diarrhoea be associated with?

A

Urgency
Tenesmus
Constitutional symptoms; eg: fever

29
Q

What is the mechanism of deranged intestinal motility causing rapid transit?

A

Inadequate time for absorption of fluid and nutrients

30
Q

What are the causes of deranged intestinal motility causing rapid transit?

A

IBS
Thyrotoxicosis
Diabetic neuropathy

31
Q

What is the mechanism of deranged intestinal motility causing slow transit and associated malabsorption?

A

Bacterial overgrowth > nutrient consumption > bile salt inactivation

32
Q

What are the causes of deranged intestinal motility causing slow transit?

A

Anatomical defects > intestinal stasis

  • Strictures
  • Blind loops
  • Surgical procedures
33
Q

What intraluminal disorders can lead to malabsorption?

A

Mechanical - mixing disorders
- Post-gastrectomy
Reduced nutrient availability
- Co-factor deficiency; eg: pernicious anaemia
- Bacterial overgrowth > nutrient consumption
Defective nutrient breakdown
- Pancreatic insufficiency; eg: chronic pancreatitis
Reduced bile salt concentration > reduced fat solubilisation
- Cholestasis
- Bacterial overgrowth

34
Q

What intramural and transport disorders can lead to malabsorption?

A 
Inadequate absorptive surface
- Intestinal resection/bypass due to disease
Diffuse mucosal disease
- Coeliac disease
- Crohn's disease
- Giardia infection
- Brush border enzyme deficiency
Mucosal absorptive defects
- Lymphoma
- Lymphatic obstruction
- Radiation damage
- Vascular problems
35
Q

What are the differential diagnoses for bloody, mucousy diarrhoea with tenesmus?

A 
Infection - dysentery
- Salmonella
- Shigella
- Yersinia
- Entamoeba histolytica
- CMV colitis
IBD
Ischaemic colitis
Radiation colitis
36
Q

How is the diagnosis of IBD confirmed?

A

Colonoscopy

Colonic biopsy

37
Q

What are the histological features of ulcerative colitis?

A

Superficial ulceration with distortion of crypts
Acute and chronic diffuse inflammatory infiltrate
Goblet cell depletion
Crypt abscesses
Lymphoid aggregates
No granulomas

38
Q

Which inflammatory bowel disease has a higher risk of colorectal cancer?

A

Ulcerative colitis

39
Q

What are the symptoms of ulcerative colitis?

A 
Frequent episodes of rectal bleeding
Urgency and tenesmus
Abdominal cramps
Weight loss
Fever
40
Q

What is the treatment for ulcerative colitis?

A

Sulphasalazine (5-ASA compound) and steroids
Start with topical therapy
Immunosuppressants used in severe/recurrent disease
For severe/refractory cases
- Biologics
- Surgery

41
Q

What part of the bowel does ulcerative colitis affect?

A

Starts at rectum
Proceeds proximally
No skip lesions

42
Q

What are the pathological features of Crohn’s disease?

A 
Focal transmural inflammation
Fissures
Ulcers
Granulomas
Healthy intestine between lesions = skip lesions
43
Q

What part of the bowel does Crohn’s disease affect?

A

Gum to bum

44
Q

What are some extra-intestinal features of Crohn’s disease?

A

Arthritis, especially sacro-ileitis
Uveitis
Rashes

45
Q

What are the symptoms of Crohn’s disease?

A 
Abdominal pain
Diarrhoea
Weight loss
Fever
Failure to thrive
46
Q

What is the treatment for Crohn’s disease?

A 
Steroids
Sulphasalazine
Immunosuppressants
- Azathioprine
- Methotrexate
Biologics
Surgery
47
Q

How is irritable bowel syndrome diagnosed?

A

Rome IV criteria
- Recurrent abdominal pain on average at least 1 day/week in last 3 months, associated with 2+ of
- Related to defaecation
- Change in frequency of stool
- Change in form of stool
Symptoms must have started at least 6 months ago
Exclude other diagnoses

48
Q

What secondary deficiencies can coeliac’s disease present with?

A

Fe
Ca
Folate
Vitamin B12

49
Q

Of what are people with coeliac’s disease at an increased risk?

A

GI cancers, especially unusual ones including

  • MALT
  • Lymphomas
50
Q

What is a screening test for coeliac’s disease?

A

Blood test measuring Abs against

  • Transglutanimase (tTG-IgA)
  • Deamidated gliadin peptides (DGP-IgG)
51
Q

What is the gold standard for diagnosis of coeliac’s disease?

A 
Small bowel biopsy showing
- Villous atrophy
- Crypt hyperplasia
- Raised intra-epithelial lymphocytes
Person has to be consuming gluten
52
Q

What can cause false negative serology results in coeliac’s disease?

A

Gluten free diet, especially if >4 weeks
IgA defiency - always concurrently order total IgA
Immunosuppression

53
Q

Which test can be used to exclude coeliac’s disease?

A

HLA-DQ2/8 gene test

54
Q

What is the epidemiology of irritable bowel syndrome?

A

15-20% of general population in Western countries

More common in females

55
Q

What sort of symptoms can irritable bowel syndrome cause?

A

Constipation-predominant
Diarrhoea-predominant
Pain-predominant
Mixed pattern

56
Q

What is the pathogenesis of irritable bowel syndrome?

A 
Serotonin key mediator
Disordered intestinal motility
Altered perception of nociceptive stimuli
Psychogenic factors
Post-infectious component in some people
57
Q

What are some triggers of irritable bowel syndrome?

A

Stress
Small bowel bacterial overgrowth
FODMAP malabsorption

58
Q

What is the first-line treatment for irritable bowel syndrome?

A

Low FODMAP diet

59
Q

What is the outline of treatment in irritable bowel syndrome?

A 
Dietary modification
- Avoiding common food triggers
- Avoiding
   - Caffeine
   - Alcohol
   - Smoking
Pharmacological therapies
- Probiotics
- Antispasmodics
- Antidiarrhoeals
- Laxatives
- Abx to treat bacterial overgrowth
Psychological therapies
- Relaxation
- CBT
- Hypnotherapy

MD2 Medicine (18 decks)

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