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.
What is the stool like in osmotic diarrhoea?
small compared to secretory
When does the diarrhoea improve/ stop in osmotic diarrhoea?
during fasting
What causes osmotic diarrhoea?
It results from the 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 can you measure in osmotic diarrhoea, and what should the results say, and is the test useful?
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).
How can osmotic diarrhoea be subdivided?
maldigestion and malabsorption
What is osmotic maldigestion diarrhoea? And when can it be seen?
refers 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 is osmotic malabsorption diarrhoea? And when can it be seen? (4)
refers 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).
What is Crohn’s disease?
lifelong condition where parts of the digestive system become inflamed
it’s one type of a condition called inflammatory bowel disease
What are the symptoms of Crohn’s? (5)
(affects people of all ages, the symptoms usually start in childhood or early adulthood)
The main symptoms are:
diarrhoea
stomach aches and cramps
blood in your poo
tiredness (fatigue)
weight loss
The symptoms may be constant or may come and go every few weeks or months. When they come back, it’s called a flare-up.
When should you see a GP for Crohn’s? (5)
See a GP if you or your child have:
blood in your poo
diarrhoea for more than 7 days
frequent stomach aches or cramps
lost weight for no reason, or your child’s not growing as fast as you’d expect
What are the treatments for Crohn’s? (3)
There’s no cure for Crohn’s disease, but treatment can help reduce or control your symptoms.
The main treatments are:
medicines to reduce inflammation in the digestive system – usually steroid tablets
medicines to stop the inflammation coming back – either tablets or injections
surgery to remove a small part of the digestive system – sometimes this may be a better treatment option than medicines
What are causes of Crohn’s?
The exact cause of Crohn’s disease is unknown.
It’s thought several things could play a role, including:
your genes – you’re more likely to get it if a close family member has it
a problem with the immune system (the body’s defence against infection) that causes it to attack the digestive system
smoking
a previous stomach bug
an abnormal balance of gut bacteria
There’s no evidence to suggest a particular diet causes Crohn’s disease.
What is diarrhoea according to the session?
3 or more loose or liquid stools per day
Where does the fluid in the GI tract come from?
1-2L drank per day
6-7L secreted into GI tract a day
What are the types of cellular transport to do with enterocytes?
transcellular and paracellular
What is the ion transport that happens at enterocytes?
What happens at enterocytes during inflammatory diarrhoea?
decreased absorption of water, leading to increased water retention in lumen
What happens at enterocytes during secretory diarrhoea?
increased secretion
chloride channels are more activated, leading to more chloride ions in the lumen and sodium and water follow
What is a pancreatic condition that causes maldigestion diarrhoea?
pancreatic exocrine insufficiency
Where does the absorbed fluid go?
lumen–> enterocytes–> capillaries
Do you understand this diagram?
How do you assess for diarrhoea?
What are the similar and not similar symptoms of IBS and IBD?
What tests do you do for diarrhoea?
FBC- look for anaemia and signs of inflammation/ infection
Urea and electrolytes- check renal function and electrolyte status
CRP- look for infection/ inflammation
Stool tests- Routine microbiology, ova, cysts and parasites (3 specimens a min of 2 days apart as ova and cysts are shed intermittently)
Blood tests- FBC, U&E, LFTs, Ca2+, Vitamin B12, folate, ferritin, TFTs, ESR/CRP, test for coeliac disease
Consider further tests such as faecal calprotectin
(think also thyroid, ovarian cancer, ESR)
What is the diagnosis?
Crohn’s disease
(the comparative pictures are for Crohn’s vs Ulcerative Colitis)
What are the differences between Crohn’s and Ulcerative Colitis?
Location of inflammation
Depth of inflammation
Pattern of inflammation
Granulomas
Crypt Abscesses
Ulcerations and Fistulas
Crypt distortion
Perianal involvement
Histological features
What are the treatments for Crohn’s?
Inducing Remission:
- corticosteroids
- aminosalicylate
- azathioprine/ mercaptopurine
- infliximab/ adalimumab
Maintaining remission:
- azathioprine/ mercaptopurine
- methotrexate
Surgery:
- bowel resection
also…
lifestyle changes e.g.,
- stop smoking (it exacerbates it)
- reduce fibre
- increase calories (high cal supplements)
- high protein
steroids during an acute flare up (oral or iv depending on severity)
