Thyrotoxicosis is often accompanied by secretory diarrhoea or
Low-volume diarrhoea is associated with irritable bowel
syndrome. Abdominal pain, bloating, dyspepsia and non-alimentary
symptoms commonly accompany irritable bowel symptoms.
Criteria have been developed to define irritable bowel syndrome
more precisely, taking account of the duration of symptoms, the
presence of abdominal pain and its relationship to defecation,
and the frequency and consistency of stools (see Rome IV criteria
for irritable bowel syndrome).
Clarify what the patient means by constipation. Use the Bristol
stool form scale (Fig. 6.7) to describe the stools. Constipation
is the infrequent passage of hard stools.
• onset: lifelong or of recent onset
• stool frequency: how often the patient moves their bowels
each week and how much time is spent straining at stool
• shape of the stool: for example, pellet-like
• associated symptoms, such as abdominal pain, anal pain
on defecation or rectal bleeding
• drugs that may cause constipation.
Constipation may be due to lack of dietary fibre, impaired
colonic motility, mechanical intestinal obstruction, impaired
rectal sensation or anorectal dysfunction impairing the process
of defecation. Constipation is common in irritable bowel syndrome.
Other important causes include colorectal cancer, hypothyroidism,
Formerly Reader in Medicine at the University of Bristol.
Fig. 6.7 Bristol stool form scale. Reproduced with kind permission of
Dr KW Heaton, formerly Reader in Medicine at the University of Bristol.
©2000, Norgine group of companies.
colorectal cancer or colonic polyps, inflammatory bowel disease,
ischaemic colitis and colonic angioectasias.
Jaundice is a yellowish discoloration of the skin, sclerae (Fig. 6.8)
and mucous membranes caused by hyperbilirubinaemia (Box 6.6).
There is no absolute level at which jaundice is clinically detected
but, in good light, most clinicians will recognise jaundice when
bilirubin levels exceed 50 µmol/L (2.92 mg/dL).
• associated symptoms: abdominal pain, fever, weight loss,
• colour of stools (normal or pale) and urine (normal or dark)
• travel history and immunisations
• use of illicit or intravenous drugs
Unconjugated bilirubin is insoluble and binds to plasma albumin;
it is therefore not filtered by the renal glomeruli. In jaundice from
unconjugated hyperbilirubinaemia, the urine is a normal colour
(acholuric jaundice; Box 6.7).
Bilirubin is conjugated to form bilirubin diglucuronide in the
liver and excreted in bile, producing its characteristic green
colour. In conjugated hyperbilirubinaemia, the urine is dark brown
due to the presence of bilirubin diglucuronide. In the colon,
conjugated bilirubin is metabolised by bacteria to stercobilinogen
and stercobilin, which contribute to the brown colour of stool.
Stercobilinogen is absorbed from the bowel and excreted in the
urine as urobilinogen, a colourless, water-soluble compound.
Melaena is the passage of tarry, shiny black stools with a
characteristic odour and results from upper gastrointestinal
bleeding. Distinguish this from the matt black stools associated
with oral iron or bismuth therapy.
Peptic ulceration (gastric or duodenal) is the most common
cause of upper gastrointestinal bleeding and can manifest with
melaena, haematemesis or both. Excessive alcohol ingestion
may cause haematemesis from erosive gastritis, Mallory–Weiss
tear or bleeding oesophagogastric varices in cirrhotic patients.
Oesophageal or gastric cancer and gastric angioectasias (Dieulafoy
lesion) are rare causes of upper gastrointestinal bleeding.
The Rockall and Blatchford scores are used to assess the
risk in gastrointestinal bleeding (Box 6.5). A profound upper
gastrointestinal bleed may lead to the passage of purple stool
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