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CSI 1b > Diarrhoea > Flashcards

Diarrhoea Flashcards

1
Q

Diarrhoea definition? Passage of…

A
  • three or more loose or liquid stools per 24 hours, and/or
  • stools that are more frequent than what is normal for the individual lasting <14, and/or
  • stool weight greater than 200 g/day

decreased absorption or increased secretion of fluid and electrolytes, or increase in bowel motility

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2
Q

Diarrhoea duration classification?

A
  • acute (<14 days)
  • persistent (>14 days)
  • chronic (>4 weeks)
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3
Q

How much fluid enters GI tract every day?

A

10 litres

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4
Q

What is the major site for re-absorption?

A

Small intestine

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5
Q

How much fluid is reabsorbed?

A

About 99% reabsorbed

0.1 litre excreted in faeces

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6
Q

Inflammatory diarrhoea causes?

A

Can be due to bacterial, viral, or parasitic infection

May develop early in course of bowel ischaemia, radiation injury, or inflammatory bowel disease

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7
Q

Inflammatory diarrhoea associated symptoms?

A

Mucoid and bloody stool
Tenesmus
Fever
Severe cramps abdominal pain

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8
Q

Infectious inflammatory diarrhoea? Volume and bowel movements

A

Small volume
Frequent bowel movements

does not usually result in volume depletion in adults

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9
Q

Most common bacterial causes of infectious diarrhoea? In US

A

Campylobacter
Salmonella
Shigella
E. coli
Clostridium difficule

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10
Q

Other causes of infectious diarrhoea?

A

Viruses (more common among children who attend day care centres)
Protozoa and parasites (common causes of acute diarrhoea in developing countries)

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11
Q

Examination of stool in inflammatory diarrhoea?

A

May show leukocytes
Tests for occult blood may be positive
Faecal calprotectin

test for faecal leukocytes - plagued by high rate of false-negatives but positive test very informative

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12
Q

Histology of GI tract in inflammatory diarrhoea?

A

Abnormal

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13
Q

Non-inflammatory diarrhoea? Volume, frequency and symptoms compared to inflammatory

A

Watery, large-volume, frequent stool (>10 to 20 per day)

volume depletion is possible due to high volume and frequency of bowel movements
no tenesmus, blood in stool, fever, or faecal leukocytes

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14
Q

Histology of GI tract in non-inflammatory diarrhoea?

A

Preserved

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15
Q

Non-inflammatory diarrhoea subdivisions?

A

Secretory diarrhoea
Osmotic diarrhoea

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16
Q

Secretory diarrhoea? Mechanism and osmotic gap

A

Altered transport of ions across mucosa -> increased secretion and decreased absorption of fluids and electrolytes from GI tract (esp. small intestine)

doesn’t decrease by fasting
low stool osmotic gap

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17
Q

Causes of secretory diarrhoea?

A

Enterotoxins
Hormonal agents
Laxative use, intestinal resection, bile salts, fatty acids

also seen in chronic diarrhoea with coeliac sprue, collagenous colitis, hyperthyroidism, and carcinoid tumours

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18
Q

Enterotoxin causes of secretory diarrhoea?

A

Vibrio cholera
Staph. a
Enterotoxigenic E. coli
Possibly HIV and rotavirus

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19
Q

Hormonal causes of secretory diarrhoea?

A

Vaso-activate intestinal peptide
Small-cell cancer of the lung
Neuroblastoma

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20
Q

Osmotic diarrhoea? Volume and mechanism

A

Stool volume relatively small, diarrhoea improves with fasting
Results from presence of unabsorbed solute (magnesium, sorbitol, mannitol) in intestinal tract that causes increased secretion of liquids into gut lumen

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21
Q

Osmotic diarrhoea tests and osmotic gap?

A

Stool electrolytes shows increased osmotic gap (>50)
Stool is always isosmotic (260-290 mOsm/L)

so stool osmotic gap test could differentiate between osmotic and secretory diarrhoea
high stool osmotic gap

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22
Q

Osmotic diarrhoea subdivisions?

A

Maldigestion
Malabsorption

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23
Q

Transcellular vs paracellular transport?

A

Transcellular transport - when solutes travel through the cell
Paracellular transport - when solutes travel around the cell (e.g. through gap junctions)

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24
Q

Water secretion into lumen?

A
  1. Chloride channels on luminal side activated, chroride ions transported into cellular lumen
  2. Causes paracellular transport of sodium from interstitial space -> lumen
  3. This creates osmotic gradient - water follows the solute so water is secreted into the lumen
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25
Q

Water absorption?

A

Sodium transporters on luminal and interstitial side cause transcellular sodium transport into capillaries - water follows into capillaries (through enterocytes)

often on empty stomach

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26
Q

How does infection cause inflammatory diarrhoea?

A

Reduced absorption
Pathogens affect interstitial lining -> affects transport and reduces water absorption
causes water retention in lumen -> diarrhoea

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27
Q

Secretory diarrhoea? Mechanism and 2 causes

A

Increased secretion
increased activation of chloride transporters -> increased secretion of water into lumen -> diarrhoea

Causes - cholera toxin, laxatives…

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28
Q

How does lactose intolerance cause maldigestion diarrhoea (osmotic)

A

Lactose not being digested into glucose (and galactose) so process of sodium absorption and water absorption does not happen

29
Q

How does pancreatic exocrine insufficiency cause maldigestion diarrhoea (osmotic)?

A

Problem with digestive enzymes - insufficient digestion of food -> sodium transporters or enterocytes not activated -> reduces transport + absorption of sodium -> reduced absorption of water and diarrhoea

30
Q

Malabsorption diarrhoea causes?

A

Sorbitol (found in proons)
Surgical resection
Bacterial overgrowth

causes water retention in lumen

31
Q

Reduced absorption causes of diarrhoea?

A

Inflammatory diarrhoea
Osmotic diarrhoea - maldigestion and malabsorption

32
Q

Cause of increased secretion diarrhoea?

A

Secretory diarrhoea

33
Q

Conjugates on drugs?

A

Drugs with large conjugates attached to them which can be digested in specific place e.g. colon - would be helpful if inflammation in colon

34
Q

Drugs to improve absorption in small intestine considerations and side effects?

A

Small intestine structures allow for maximal absorption, leading to high systemic availability of any absorbed medication

causes increased side effect profile of medications due to enhanced absorption

35
Q

Anti-inflammatory drugs problem?

A

Anti-inflammatory drugs are designed for colon absorption, so only effective if inflammation causing diarrhoea originates in colon

tend to be potent drugs with significant side effects

36
Q

Targeting transporters for secretory diarrhoea?

A

Intestinal transporters implicated in diarrhoea process, e.g. SGLT-2, sodium channels, sodium-glucose transporter
Targets are expressed throughout the body (causing potential side effects)
aim is to reduce secretion and/or to increase absorption

37
Q

Maldigestion drugs difficulty and strategies?

A

Difficult to enhance endogenous enzyme activity
Exogenous enzymes are susceptible to digestive process
Strategies - enteric coating, probiotics, gene therapy

38
Q

Gene therapy risks?

A

Unwanted immune response, incorrect cell targeting

39
Q

IBS symptoms?

A

Alternating constipation and diarrhoea
Bloating

Abdominal pain
Faecal urgency
Mucus in stool
Fatigue

40
Q

IBD symptoms?

A

Weight loss
Fever
Blood in stool
raised faecal calprotectin unlike in IBS

Abdominal pain
Faecal urgency
Mucus in stool
Fatigue

41
Q

IBS and IBD shared symptoms?

A

Abdominal pain
Faecal urgency
Mucus in stool
Fatigue

42
Q

Organic cause of diarrhoea investigations?

A
  • FBC - check for amaemia and signs of inflammation, LFT, pancreatic enzymes, TSH, ESR (acute inflammation), CA-125 (ovarian cancer)
  • Urea and electrolytes - check renal function and electrolyte status
  • CRP - look for signs of infection/inflammation
  • Stool MC&S (for infective), qFIT (microscopic blood in stool), faecal calprotectin (inflammation in bowel)
  • X-ray, colonoscopy
43
Q

Stool tests for organic diarrhoea?

A

Stool tests - routine microbiology, ova cysts and parasites (3 specimens a min of 2 days apart as ova and cysts are shed intermittently), calprotectin

44
Q

Blood tests for diarrhoea?

A

FBC, U&E, LFTs, Ca2+, B12, folate, ferritin, TFTs, ESR/CRP, test for coeliac

Faecal calprotectin if bloods show abnormality

45
Q

Types of inflammatory bowel disease?

A

Crohn’s disease
Ulcerative colitis

46
Q

Features of Crohn’s vs ulcerative colitis? Lesions and layers

A

Crohn’s - Non-continuous lesions or “skip lesions” in Crohn’s, cobblestone appearance. Affects all layers of bowel

UC - Continuous and uniform, no breaks of normal bowel. Affects mucosa (and submucosa) only

47
Q

Location of Crohn’s vs ulcerative colitis?

A

Crohn’s - anywhere, mouth to anus in skip lesions (commonly starts at terminal ileum)

UC - primarily affects colon and rectum, usually starts in rectum then spreads upwards. Only affects large bowel

48
Q

Depth of inflammation in Crohn’s vs ulcerative colitis?

A

Crohn’s - transmural involvement, affects all layers of intestinal wall

UC - just mucosa, continuous inflammation

49
Q

Granulomas in Crohn’s vs ulcerative colitis?

A

More common in Crohn’s (non-caseating and increased goblet cells)

Could be due to more macrophages in Crohn’s, compared to more neutrophils in UC which have a shorter half life

50
Q

Crypt abscesses in Crohn’s vs ulcerative colitis?

A

More common in Crohn’s

crypt distortion without branching in UC

51
Q

Ulcerations and fistulas in Crohn’s vs ulcerative colitis?

A

Crohn’s - fistulas and deep ulcerations may be present, perianal area fistulas or skin tags, more likely perianal involvement

UC - superficial ulcerations without fistulas, broad-based ulcers and pseudopolyps common

52
Q

Conservative management for Crohn’s disease?

A

Lifestyle (smoking cessation, avoiding foods that trigger flare ups so dietary modification)
reducing fibre
High calorie supplements

53
Q

Medical management to induce remission of Crohn’s?

A

Steroids (oral - prednisolone, IV - hydrocortisone) for a flare up
Aminosalicylate
Azathioprine/mercaptopurine
Infliximab/adalimumab

54
Q

Medical management to maintain remission of Crohn’s?

A

Immunosuppressants
- Azathioprine/mercaptopurine
- Methotrexate

55
Q

Surgical management of Crohn’s?

A

Bowel resection

56
Q

Main symptoms of Crohn’s?

A

Diarrhoea
Stomach aches and cramps
Blood in poo
Tiredness
Weight loss

high temp, nausea and vomiting, joint pains, sore and red eyes, patches of painful, red, swollen skin, mouth ulcers

57
Q

Causes of Crohn’s?

A

Genes
Autoimmune
Smoking
Previous stomach bug
Abnormal balance of gut bacteria

58
Q

Specialist tests for Crohn’s?

A

Colonoscopy
Biopsy
MRI or CT

59
Q

Treatment for Crohn’s? (NHS website)

A

Steroids
Liquid diet
Immunosuppressants
Biological medicines
Surgery

60
Q

Living with Crohn’s? (NHS website)

A

ibuprofen can make it worse
Vaccinations should be taken
Tell GP about pregnancy
Contraception may not work the same (OCP)
Cancer screening - BOWEL CANCER

61
Q

Normal stool osmotic gap values?

A

Between 50 and 100

62
Q

Smoking in Crohn’s vs UC?

A

Smoking risk factor for Crohn’s
Smoking protective against UC

63
Q

Only diagnostic investigations for IBD?

A

Colonoscopy and biopsy

64
Q

Corticosteroid example for Crohn’s?

A

Prednisolone

65
Q

Immunosuppressants for Crohn’s?

A
  • Azathioprine
  • Mercaptopurine
  • Methotrexate
66
Q

Biologics for Crohn’s?

A
  • Adalimumab
  • Infliximab
67
Q

Lifestyle precautions for Crohn’s? Diet, medication, recommended, avoid

A

Diet - enteral nutrition for children, healthy for adults, stop smoking
Medication - NSAIDs can interact with Crohn’s medication
Recommended - flu and pneumococcal jab
AVOID - live vaccines

68
Q

Maldigestion diarrhoea mechanism and 2 causes?

A

Impaired digestion of nutrients within intestinal lumen or brush border membrane of mucosal epithelial cells.

In pancreatic exocrine insufficiency and lactase deficiency.

69
Q

Malabsorption diarrhoea? Mechanism and some causes

A

Impaired absorption of nutrients

In small bowel bacterial overgrowth, mesenteric ischaemia, post bowel resection, mucosal disease (coeliac)

CSI 1b (8 decks)

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