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MD2 Medicine > Diarrhoea and Malabsorption > Flashcards

Diarrhoea and Malabsorption Flashcards

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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?

Study These Flashcards
A

Altered membrane permeability > exudation of

  • Protein
  • Blood
  • Mucus
25
What are the common causes of inflammatory diarrhoea?
``` Invasive bacteria - Shigella - Salmonella - Campylobacter - Clostridium difficile Entamoeba hystolytica CMV colitis IBD ```
26
What is the stool volume in inflammatory diarrhoea?
Usually small
27
Are there leukocytes and erythrocytes present in the stool in inflammatory diarrhoea?
Yes, increased RBCs and leukocytes
28
What other symptoms can inflammatory diarrhoea be associated with?
Urgency Tenesmus Constitutional symptoms; eg: fever
29
What is the mechanism of deranged intestinal motility causing rapid transit?
Inadequate time for absorption of fluid and nutrients
30
What are the causes of deranged intestinal motility causing rapid transit?
IBS Thyrotoxicosis Diabetic neuropathy
31
What is the mechanism of deranged intestinal motility causing slow transit and associated malabsorption?
Bacterial overgrowth > nutrient consumption > bile salt inactivation
32
What are the causes of deranged intestinal motility causing slow transit?
Anatomical defects > intestinal stasis - Strictures - Blind loops - Surgical procedures
33
What intraluminal disorders can lead to malabsorption?
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
What intramural and transport disorders can lead to malabsorption?
``` 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
What are the differential diagnoses for bloody, mucousy diarrhoea with tenesmus?
``` Infection - dysentery - Salmonella - Shigella - Yersinia - Entamoeba histolytica - CMV colitis IBD Ischaemic colitis Radiation colitis ```
36
How is the diagnosis of IBD confirmed?
Colonoscopy | Colonic biopsy
37
What are the histological features of ulcerative colitis?
Superficial ulceration with distortion of crypts Acute and chronic diffuse inflammatory infiltrate Goblet cell depletion Crypt abscesses Lymphoid aggregates No granulomas
38
Which inflammatory bowel disease has a higher risk of colorectal cancer?
Ulcerative colitis
39
What are the symptoms of ulcerative colitis?
``` Frequent episodes of rectal bleeding Urgency and tenesmus Abdominal cramps Weight loss Fever ```
40
What is the treatment for ulcerative colitis?
Sulphasalazine (5-ASA compound) and steroids Start with topical therapy Immunosuppressants used in severe/recurrent disease For severe/refractory cases - Biologics - Surgery
41
What part of the bowel does ulcerative colitis affect?
Starts at rectum Proceeds proximally No skip lesions
42
What are the pathological features of Crohn's disease?
``` Focal transmural inflammation Fissures Ulcers Granulomas Healthy intestine between lesions = skip lesions ```
43
What part of the bowel does Crohn's disease affect?
Gum to bum
44
What are some extra-intestinal features of Crohn's disease?
Arthritis, especially sacro-ileitis Uveitis Rashes
45
What are the symptoms of Crohn's disease?
``` Abdominal pain Diarrhoea Weight loss Fever Failure to thrive ```
46
What is the treatment for Crohn's disease?
``` Steroids Sulphasalazine Immunosuppressants - Azathioprine - Methotrexate Biologics Surgery ```
47
How is irritable bowel syndrome diagnosed?
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
What secondary deficiencies can coeliac's disease present with?
Fe Ca Folate Vitamin B12
49
Of what are people with coeliac's disease at an increased risk?
GI cancers, especially unusual ones including - MALT - Lymphomas
50
What is a screening test for coeliac's disease?
Blood test measuring Abs against - Transglutanimase (tTG-IgA) - Deamidated gliadin peptides (DGP-IgG)
51
What is the gold standard for diagnosis of coeliac's disease?
``` Small bowel biopsy showing - Villous atrophy - Crypt hyperplasia - Raised intra-epithelial lymphocytes Person has to be consuming gluten ```
52
What can cause false negative serology results in coeliac's disease?
Gluten free diet, especially if >4 weeks IgA defiency - always concurrently order total IgA Immunosuppression
53
Which test can be used to exclude coeliac's disease?
HLA-DQ2/8 gene test
54
What is the epidemiology of irritable bowel syndrome?
15-20% of general population in Western countries | More common in females
55
What sort of symptoms can irritable bowel syndrome cause?
Constipation-predominant Diarrhoea-predominant Pain-predominant Mixed pattern
56
What is the pathogenesis of irritable bowel syndrome?
``` Serotonin key mediator Disordered intestinal motility Altered perception of nociceptive stimuli Psychogenic factors Post-infectious component in some people ```
57
What are some triggers of irritable bowel syndrome?
Stress Small bowel bacterial overgrowth FODMAP malabsorption
58
What is the first-line treatment for irritable bowel syndrome?
Low FODMAP diet
59
What is the outline of treatment in irritable bowel syndrome?
``` 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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