2.7// Diarrhoea Flashcards
How can diarrhoea be defined in a clinical setting?
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?
Based on duration, diarrhoea is classified as:
Acute (≤14 days)
Persistent (>14 days), or
Chronic (>4 weeks).
How much fluid enters the gastrointestinal tract every day, and what is in that fluid?
Normally approximately 10 litres of fluid consisting of ingested food and drink, in addition to secretions from the salivary glands, stomach, pancreas, bile ducts, and duodenum, enters the gastrointestinal tract every day.
Where is a major site for reabsorption?
small intestine
How much of the fluid is reabsorbed, and what happens to the rest?
99%, leaving 0.1L to be excreted in the faeces
When does diarrhoea occur?
Diarrhoea occurs when various factors interfere with this normal process (of reabsorption), resulting in decreased absorption or increased secretion of fluid and electrolytes, or increase in bowel motility.
What are the types of diarrhoea?
1) inflammatory diarrhoea
2) Non-inflammatory diarrhoea
2.1)secretory
2.2) osmotic
What causes inflammatory diarrhoea?
This indicates the presence of an inflammatory process, which can be due to bacterial, viral, or parasitic infection, or may develop early in the course of bowel ischaemia, radiation injury, or inflammatory bowel disease.
What is inflammatory diarrhoea associated with?
It is usually associated with mucoid and bloody stool, tenesmus, fever, and severe crampy abdominal pain.
What is the stool like normally with inflammatory diarrhoea, and what does that result in?
Infectious inflammatory diarrhoea is usually small in volume, with frequent bowel movements.
It therefore does not usually result in volume depletion in adults, but may do so in children or older adults.
What is the most common cause of inflammatory diarrhoea in the US?
The most common cause of infectious diarrhoea in the US is bacterial infection
Viruses are more common among children who attend day care centres.
Protozoa and parasites are common causes of acute diarrhoea in developing countries.
What area of the body is the histology abnormal in inflammatory diarrhoea?
GI tract
What is the stool like in non-inflammatory diarrhoea?
This is usually watery, large-volume, frequent stool (>10 to 20 per day).
Is volume depletion possible in non-inflammatory diarrhoea?
yes due to high volume and frequency of bowel movement
What symptoms are absent in non-inflammatory diarrhoea? (4)
There is no tenesmus, blood in the stool, fever, or faecal leukocytes.
What is the histology of the GI tract in non-inflammatory diarrhoea?
architecture is preserved
How can non-inflammatory diarrhoea be subdivided?
secretory and osmotic diarrhoea
What is secretory diarrhoea?
There is an 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.
Secretory diarrhoea tends not to decrease by fasting.
What are some examples of causes for secretory diarrhoea?
Enterotoxins: these can be from infection such as Vibrio cholerae, Staphylococcus aureus, enterotoxigenic E coli, and possibly HIV and rotavirus.
Hormonal agents: vaso-active intestinal peptide, small-cell cancer of the lung, and neuroblastoma.
Laxative use, intestinal resection, bile salts, and fatty acids.
It is also seen in chronic diarrhoea with coeliac sprue, collagenous colitis, hyperthyroidism, and carcinoid tumours.