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What is considered a slow capillary refill time?



What are the signs of moderate dehydration?

• Irritability
• Thirst


What are the signs of severe dehydration?

• Lethargy
• Unable to drink


What is the definition of diarrhoea?

3 or more loose/watery stools within 24 hours.


What are the four causes of diarrhoea?

1) Infective
2) Inflammatory
3) Steatorrhoea
4) Functional


What is infective diarrhoea?

This is diarrhoea caused by an infective agent. It typically has sudden onset and comes with associated fever and cramp-like abdominal pain.


What is Inflammatory diarrhoea?

This is diarrhoea caused by an inflammatory condition such as IBD. Often occurs with a blood stained stool.


What is steatorrhoea?

This is pale, offensive floating stool. It often coincides with weight loss and appetite loss.
• Giardiasis and Coeliac disease.


What is functional diarrhoea?

Small volume and often semi-formed.


What are the two main mechanisms of diarrhoea?

Osmotic and Secretory


What is osmotic diarrhoea?

• This is where there are large amounts of hypertonic substances in the lumen which may be due to substances that can't be digested, general malabsorption.
• Moderate volume
• Stops on fasting
• High osmolality of stool


What is secretory diarrhoea?

• Active secretion of fluid and electrolytes from gut wall which may be due to irritants and hormones.
• High volume
• Continues on fasting (Still secreting)
• Normal osmolality of stool


Which mechanism of diarrhoea is halted by fasting?



Which mechanism of diarrhoea produces high volume of stools?



Which mechanism of diarrhoea produces stools with a high osmolality?



What are the initial investigations for diarrhoea?

Stool sample - Osmolality, microbiology, culture and sensitivity.


What investigation may be needed for persistent diarrhoea?

Sigmoidoscopy and rectal biopsy.


What is the initial stage of treatment for diarrhoea?

Assess fluid status and rehydrate if required.


Once fluid status is assessed and managed how should acute diarrhoea be managed?

• Treat cause - Antibiotics/ stop drugs causing.
• Treat diarrhoea - Loperamide - Opioid agonist, decreases motility and increase anal sphincter tone.
• (Infective diarrhoea is often self-limiting so let it run it's course)


101 Diarrhoea: What are the three steps of treatment for acute diarrhoea?

1) Replace fluids.
2) Address the underlying cause.
3) Stop Diarrhoea.


101 Diarrhoea: Describe (briefly) how oral rehydration solutions work?

They are composed of glucose and sodium, which get actively pumped into the cell, this causes water to follow and the glucose and sodium are then excreted.


101 Diarrhoea: What is the main drug used to stop acute diarrhoea? What class is it?

Loperamide, anti-motility drug.


101 Diarrhoea: What is the mechanism of Loperamide?

It is an opioid receptor agonist which causes decreased motility of the bowel and increases the tone of the anal sphincter.


101 Diarrhoea: What is the role of Racecadotril and what is it's mechanism?

Treatment of acute diarrhoea. Inhibits enkephalinase, therefore prolonging the life of enkephalins, which are opioid receptor agonists, causing decreased motility of the bowel.


101 Diarrhoea: How long would you expect a skin pinch on a child abdomens to revert back to normal shape in a healthy child?

Immediate, 1s=slow, ≥2s = very slow.


101 Diarrhoea: In what part of the bowel does the majority of fluid resorption take place?



101 Diarrhoea: By which part of the bowel is the absorption of <95% of macronutrients completed by?

Distal jejenum


101 Diarrhoea: Which part of the bowel has specialised transport mechanisms for bile acids and Vitamin B12-IF?

Distal Ileum


101 Diarrhoea: What role does the colon play in nutrient absorption?

Carbohydrate digestion and absorption, enzymes produced by colonic bacteria break the carbohydrates into short-chain fatty acids which can then be absorbed.


101 Diarrhoea: Diseases affecting which part of the bowel will result in greater amount of diarrhoea?

Small intestine (predominantly jejunum) since this is responsible for water resorption. If the colon receives more than 4L water a day, then diarrhoea will result.


101 Diarrhoea: What is the osmotic gap?

This is the difference between the osmolality of the colon contents and bodily fluids.


101 Diarrhoea: What is the osmotic gap in secretory diarrhoea? What accounts for this difference?

Around 10 mOsm/kg, electrolyte resorption is lower so sodium, potassium and their counter-ions account for most of the osmotic gap.


101 Diarrhoea: What is the osmotic gap in osmotic diarrhoea? What accounts for the difference?

Mostly carbohydrates and magnesium ions.


101 Diarrhoea: If the osmotic gap is greater than 50mOsm/kg, what is the likely cause?

An ingested substance that cannot be easily absorbed.


101 Diarrhoea: What is the usual osmolality of plasma?



101 Diarrhoea: What is the WHO definition of diarrhoea?

Loose or watery stools (that take the form of the container they are in), ≥3 times in a 24 hour period.


101 Diarrhoea: What is dysentery?

Small volume, bloody, mucoid stools and abdominal pain.


101 Diarrhoea: What are the two main types of diarrhoea?

Secretory and Osmotic.


101 Diarrhoea: What is the stool volume, and response to fasting of osmotic diarrhoea?

Moderately increased.
Stops in response to fasting.


101 Diarrhoea: What is the stool volume, and response to fasting of secretory diarrhoea?

Very large.
No response to fasting.


101 Diarrhoea: Aside from osmotic and secretory diarrhoea, what is the third type of diarrhoea?



101 Diarrhoea: What are the main causes of inflammatory diarrhoea?

Food sensitivity.
Auto-immune disease.


101 Diarrhoea: What is the common cause of increased intestinal fluid secretion? Give an example.

Rotavirus, ETEC, Cholera.


101 Diarrhoea: Give some causes and examples of diarrhoea caused by an osmotically active substance.

• Malabsorption: CHO/protein - Lactose intolerance
• Rapid gut transit - IBS, Toddlers Diarrhoea, Stimulant laxative.


101 Diarrhoea: Give some causes of steatorrhea and give examples.

• Malabsorption: Fat - Pancreatic disease, Coeliac Disease


101 Diarrhoea: Give some causes and examples of inflammatory diarrhoea.

• IBD - Crohns, UC
• Dysentery - Shigella, campylobacter
• Other - Radiation enteritis.


101 Diarrhoea: What are the main consequences of secretory diarrhoea?

• Fluid loss leading to dehydration.
• Electrolyte loss leading to disordered physiology.


101 Diarrhoea: What are the consequences of osmotic dehydration?

• Loss of nutrients leading to malnutrition.


101 Diarrhoea: A 28yr old woman, episodes of abdominal bloating and watery diarrhoea lasting 1-2 days for the last 6 months, no blood or mucus.

IBS (spastic colon/ functional diarrhoea).


101 Diarrhoea: What is the treatment for IBS?

Reassurance, anti-spasmodics, anti-diarrhoeal medication.


101 Diarrhoea: UK toddler, with watery diarrhoea more than 10x in 24hrs, some fever and vomitting, other children at playgroup have also been suffering. Likely diagnosis?



101 Diarrhoea: What is rotavirus? What is the treatment?

RNA virus, with multiple mechanisms causing diarrhoea.

The virus is self-limiting within 4-5 days, so only oral rehydration is needed.


101 Diarrhoea: 19 year old student just back from
India with Pale, foul-smelling, greasy stools that float +
difficult to flush. x 3-5/day for 3 weeks, May be “explosive”,
Lost a lot of weight – “two clothes sizes”,Feels generally unwell, nauseous and very tired. Likely diagnosis?



101 Diarrhoea: What is giardiasis, how is it treated and diagnosed?

Caused by giardia parasite, that causes steatorrhoea.

It is diagnosed by microscopy of three stool samples.

Treated by metronidazole.


101 Diarrhoea: A 40yr old lady has acute onset diarrhoea at a conference in bulgaria. She has had two-days of frequent and loose stools, has been unable to leave bathroom. Is very thirsty. Likely diagnosis?

Travellers Diarrhoea


101 Diarrhoea: Which organism is the common cause of travellers diarrhoea? What is the treatment?

ETEC - Enterotoxigenic Escherichia coli.
Usually self-limiting, but severe.


101 Diarrhoea: What is c-diff?

•Gram positive bascillus.
• Highly infectious - requires barrier nursing.
• Wide spectrum - from self-limiting to severe colitis.
• Treated with metronidazole / vancomycin +/- faecal enema.


101 Diarrhoea: What are the signs of over-rehydration?

• Increasing HR
• Respiratory Distress
• Crackles in lung fields
• Hepatomegaly
• Oedema


101 Diarrhoea: How should fluid management differ in those with hypernatraemic shock?

• Fluid replacement should be over a 48hr period not 24hrs.
• Also slowly replace serum Na+.


101 Diarrhoea: What are the signs of SAM? (severe acute malnutrition)

• Loss of subcutaneous fat and muscle wasting.
• Angular stomatitis.
• Smooth tongue.
• Conjunctival and palmar pallor.
• Hyper/hypo- pigmentation.


101 Diarrhoea: What are the problems with assessing a child with diarrhoea, who also has SAM?

• The clinical signs of shock and dehydration become unreliable.
• If fluids are replaced parenterally it can cause severe deterioration.
• In SAM the Na/K pump is broken resulting in a high body concentration of Na+.


101 Diarrhoea: How should fluid management be performed in a patient with SAM (severe acute malnutrition)?

• Oral fluids
• Reduced concentrations of Na+


101 Diarrhoea: What are the red flags for dehydration to develop into shock? (There are six)

• Appears to be unwell or deteriorating.
• Altered responsiveness.
• Sunken eyes.
• Tachycardia.
• Tachypnoea
• Reduced skin turgor.


101 Diarrhoea: What is dysentery?

• Small volume, bloody, mucoid stools, abdominal pain.


101 Diarrhoea: What is the WHO definition of diarrhoea?

Three or more loose or watery stools in a 24-hour period.


101 Diarrhoea: What is a type 1 and type 7 stool on the Bristol chart?

• Type 1 - Rabbit Droppings
• Type 7 - Gravy


101 Diarrhoea: What are the two main types of diarrhoea?

Osmotic and secretory


101 Diarrhoea: Describe osmotic diarrhoea. (In terms of volume, response to fasting, osmolality and ion gap)

• Moderately increased.
• Diarrhoea will cease in response to fasting.
• Osmolality is normal to increased.
• Ion gap is ≥100 mOsm/kg


101 Diarrhoea: Describe secretory diarrhoea. (In terms of volume, response to fasting, osmolality and ion gap)

• Very large volume.
• Diarrhoea continues despite fasting.
• Osmolality is normal.
• Ion gap is ≤100 mOsm/kg


101 Diarrhoea: Inflammatory diarrhoea is the third main type (after secretory and osmotic), what are the main causes of it?

• Infection
• Auto-immune (IBD)
• Food sensitivity (Coeliac, CMP)


101 Diarrhoea: Give 3 examples of pathology that leads to infective diarrhoea.

• Cholera
• Rotavirus


101 Diarrhoea: How does Rotavirus typically present, how is it diagnosed, what is the management?

• Typically a toddler with sudden onset watery, diarrhoea, no blood. - Comes in batches (Children at playgroup etc)
• RNA virus diagnosed with stool virology.
• Management is oral rehydration fluids (Self-limiting after 4-5 days)


101 Diarrhoea: Gap student back from India with pale, foul-smelling, greasy stools that float. What is the diagnosis and management?

• Giardiasis (A parasite that can infect your bowels and cause osmotic diarrhoea).
• Diagnosis is through microscopy of 3 stool specimens.
• Management is Tinidazole or metronidazole.


101 Diarrhoea: What pathogen is responsible for traveller's diarrhoea?

• ETEC - Enterotoxigenic Escherichia coli
• Attaches the the mucosa and produces toxins, severe but usually self limiting.


101 Diarrhoea: What is the management for Clostridium difficile?

• Barrier nursing
• Metronidazole/vancomycin
• Faecal enema.


101 Diarrhoea: What do oral rehydration solutions contain?

• Water
• Sodium Chloride 90mmol/L
• Glucose 60mmol/L
• Osmolality of 240 mOsm/L


101 Diarrhoea: What should the dose of ORS be?

200ml after each loose motion.


101 Diarrhoea: Which adverse drug reactions can cause diarrhoea?

• Antibiotics - Altering gut flora and increasing gut motility.
• NSAIDs - Irritation and inflammation of the gut.
• Digoxin - Causes imbalance of ions in gut.
• Orlistat - Fat in the gut.
• Magnesium - Osmotic effect.


101 Diarrhoea: What drug is used to stop diarrhoea? What is it's mechanism of action?

• Opioid receptor agonist
• Decreases motility of gut and increases the tone of the anal sphincter leading to increased transit time.


101 Diarrhoea: What is the dose of loperamide? What are the side effects?

• 4mg initially, then 2mg further with each loose stool.
• Side-effects include abdominal cramps & bloating.


101 Diarrhoea: One of the complications of loperamide is that it may cause constipation in some patients. Which medication may be used instead which has a reduced risk of causing constipation?

• Racecadotril
• Inhibits enkephalinase thereby prolonging the action of enkephalins.
• This reduces hyper-secretion without affecting transit time.