Diahorrea Flashcards
How does the patient present?
Terrible diarrhoea 6 weeks but it has gotten much worse Tummy pain Could not wait to see GP 3-4 a day for a month 8x recently Bad overnight Liquid, brown, sometimes blood from wiping Sample all clear from GP Weight loss - 7kg Tired - no energy Adopted Smokes 5 a day
How does she describe the pain?
Comes and goes
Left side
No change after opening bowels
How can diarrhoea be defined?
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 days, and/or
Stool weight greater than 200 g/day.
How can diarrhoea be classified?
Acute (≤14 days)
Persistent (>14 days), or
Chronic (>4 weeks)
Describe the basic pathophysiology of diarrhoea?
10L of fluid enters GI tract daily
Small intestine responsible for reabsorbing (99%)
0.1L excreted in faeces
In diarrhoea there is decreased reabsorption or increased secretion
Or increase in bowel motility
From where is fluid secreted into the GI tract?
Food Drink Salivary glands Stomach Pancreas Bile ducts Duodenum
What are the two types of diarrhoea?
Inflammatory
Non-inflammatory
What can cause inflammatory diarrhoea?
Material
Viral
Parasitic
Or early bowel ischaemia, radiation injury or IBD
What are the associated symptoms of inflammatory diarrhoea?
Mucoid and bloody stool
Tenesmus
Fever
Severe crampy abdominal pain
What are the main features of the diarrhoea in inflammatory diarrhoea?
Small in volume
Frequent bowel movements
What are the most common causes of inflammatory diarrhoea?
Campylobacter, Salmonella, Shigella, Escherichia coli, or Clostridium difficile
In who is virus related diarrhoea common in?
Children who attend day care centres
What are the most common causes of acute diarrhoea in developing countries?
Protozoa and Parasites
What findings might be found in inflammatory diarrhoea?
Examination of the stool may show leukocytes, and tests for faecal occult blood may be positive.
The test for faecal leukocytes is plagued by a high rate of false-negative results leading to low sensitivity, but a positive test is very informative.
What are the main features of non-inflammatory diarrhoea?
watery, large-volume, frequent stool (>10 to 20 per day).
Volume depletion is possible due to high volume and frequency of bowel movements.
There is no tenesmus, blood in the stool, fever, or faecal leukocytes.
Histologically the GI architecture is preserved.
What can non-inflammatory diarrhoea be further divided into?
Secretory
Osmotic
What happens in secretory diarrhoea?
Altered transport of ions across the mucosa
which results in increased secretion and decreased absorption of fluids and electrolytes from the GI tract
especially in the small intestine
What causes secretory diarrhoea?
Enterotoxins Hormonal agents Laxative use Intestinal resection Bile salts and fatty acids
Where can enterotoxins be from?
Vibrio cholerae,
Staphylococcus aureus
enterotoxigenic E coli
and possibly HIV and rotavirus.
What hormonal agents can cause secretory diarrhoea?
Vaso-active intestinal peptide
Small-cell cancer of the lung
Neuroblastoma
What conditions can secretory diarrhoea be seen in?
Coeliac sprue
Collagenous colitis Hyperthyroidism
Carcinoid tumours
What are the features of osmotic diarrhoea?
Smaller stool volume
Improves or stops with fasting
What does osmotic diarrhoea result from?
presence of unabsorbed or poorly absorbed solute (magnesium, sorbitol, and mannitol)
in the intestinal tract
that causes an increased secretion of liquids into the gut lumen
What tests are done with osmotic diarrhoea?
Measuring stool electrolytes shows an increased osmotic gap (>50), but the test has very limited practical value. Stool (normal or diarrhoea) is always isosmotic (260 to 290 mOsml/L).
What can osmotic diarrhoea be subdivided to?
Maldigestion
Malabsorption
What does maldigestion refer to?
Impaired digestion of nutrients within the intestinal lumen or at the brush border membrane of mucosal epithelial cells.
It can be seen in pancreatic exocrine insufficiency and lactase deficiency
What does malabsorption refer to?
Impaired absorption of nutrients.
It can be seen in small bowel bacterial overgrowth, in mesenteric ischaemia, post bowel resection (short bowel syndrome), and in mucosal disease (coeliac disease)
How much fluid is secreted into GI tract?
6-7 litres
How much fluid is lost in faeces?
0.1L
What happens to the fluid that is not excreted?
Gets absorbed via the walls of the small and large intestine
Why does fluid enter enterocytes?
There are lots of solutes in enterocytes
What happens in inflammatory diarrhoea (enterocytes)?
Destruction of the epithelium due to inflammation
Enterocytes cannot absorb fluids
Excess fluid in lumen
What happens in secretory diarrhoea (enterocytes)?
Ion channels become wrongly activated so solutes moves into the lumen
E.g. Cholera - chloride channel on enterocyte membrane becomes activates
Fluid follows the chloride
What happens in maldigestion diarrhoea (enterocytes)?
Solutes are not able to digest
Products remain in lumen - high solute concentration
Fluid moves to lumen
E.g. lactose intolerance
What happens in malabsorption diarrhoea (enterocytes)?
Solutes not absorbed by enterocytes
E.g. prunes
Sorbitol is not absorbed by enterocytes
Water is retained
What drug could help inflammatory?
Anti-cytokines e.g. Anti-TNF