Diarrhoea is defined as the loss of at least ___mls of fluid per day from the GI tract.
500
Which ion does water follow into GI cells?
Na+
Water moves into GI tract cells by ___.
osmosis
Which transporter couples the influx of glucose and Na+ into enterocytes?
SGLT1
Apart from glucose, which other molecule is sodium ion influx coupled to?
Amino acid influx
Which types of GI tract infection can cause diarrhoea?
Viral
Bacterial
Parasitic
What is the most common bacterium causing diarrhoea in the UK?
Campylobacter jejuni
Which bacterium most commonly causes Traveller’s diarrhoea?
EnteroTOXIC E. coli
What non-infectious GI diseases can cause diarrhoea?
IBD
IBS
Lactase deficiency
Why does hyperthyroidism cause diarrhoea?
Increased motility
What infection can the use of broad spectrum antibiotics cause?
Clostridium difficile
leads to colitis, diarrhoea
Increased levels of which molecules lead to increased expression of channels causing increased secretion into the gut?
cAMP
Toxins produced by infectious agents stimulate the enzyme ___ ___, which increase the levels of ____, which increases gut secretion causing diarrhoea.
adenylyl cyclase , cAMP/?cGMP
Diarrhoea can lead to ___ due to water loss.
dehydration
Diarrhoea can lead to ___ ___ due to bicarbonate loss.
metabolic acidosis
Diarrhoea can lead to ___ due to potassium loss.
hypokalaemia
Which disease, causing profuse watery diarrhoea, can be fatal if severe?
Cholera
What is the first line therapy for severe diarrhoea?
Fluid replacement (oral/IV)
Is coupled glucose/Na absorption affected by diarrhoea?
No - this is why fluid replacement therapy works
Which channel is used in rehydration therapy?
SGLT1
Why is salt solution used in rehydration therapy?
Takes advantage of coupled glucose/Na transport through SGLT1
And then water follows Na, causing rehydration
What do oral rehydration fluids contain?
Glucose
Sodium
to take advantage of SGLT1 ⇒ rehydration
Why are antibiotics used in a limited role in managing diarrhoea?
Most infections are VIRAL (rotavirus, norovirus)
Most bacterial infections are self-limiting so what’s the point in using antibiotics
Antibiotics are useful in (self-limiting / severe) diarrhoea.
severe
Anti-motility agents (loperamide, opiates) are only used in (mild / severe) cases of diarrhoea.
mild
you want the mucosa and toxins to be flushed out of the system - anti-motility agents slow this down
Opioids cause ___ by decreasing the rate of peristalsis and constricting sphincters.
constipation
Does the body develop a tolerance to the constipating effects of opioids?
No
What are some anti-motility agents used in diarrhoea?
Loperamide (imodium)
Diphenoxylate
Codeine
Why is atropine added to the antimotility agent diphenoxylate?
Discourages abuse of diphenoxylate through side effects (nausea, headache, weakness, blurred vision)
What is constipation?
Production of hard stools requiring straining to pass
and/or
sense of incomplete defecation
What is the higher strength version of a laxative?
Purgative
Many drugs act as laxatives in ___ doses and purgatives in ___ doses.
(low / high)
low , high
Which drugs should not be used when there is physical obstruction in the bowel?
Laxatives
Purgatives
Patients with ___ ___ may abuse laxatives to lose weight.
eating disorders
Why are patients with hernia, angina, eye surgery indicated for laxatives?
Straining increases intra-abdominal pressure which will exacerbate the condition
Why would laxatives be given to haemorrhoid patients?
Rectal bleeding risk
The use of which class of drug causes constipation and indicates the use of laxatives?
Opioids