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On to today's topic:
Irritable bowel syndrome is a diagnosis that is being handed
out much more readily these days, and it is often featured/referenced in pop
culture (usually in a comical way). But what is IBS exactly? It is much more real
and severe than you think! So this week let’s find out more about this
mysterious disease.
To start off, irritable bowel syndrome is a form of
functional bowel disease (which means that although the organs seem normal,
there are still signs that something is wrong). Irritable bowel is more than a
label for unexplained GIT symptoms because although many investigations come
back normal (indicating normal anatomy), there is often abnormal motility. It
can also be associated with abnormal perception of intestinal activity as well;
however while psychological stress may increase IBS symptoms, it probably does
not cause IBS. IBS affects 20% of North Americans, more so females than males;
and the onset of symptoms usually start in young adulthood.
There are four types of IBS: IBS with diarrhea, IBS with
constipation, IBS with mixed type (involving both diarrhea and constipation),
and IBS un-typed (insufficient abnormality in stool to fit into any one
category).
IBS is essentially a syndrome of pain.
Things that are definitely NOT IBS:
1.
Pain NOT relieved by passing of stools
2.
Patient waking up at night due to pain
3.
Blood in the stools
4.
White blood cells in stools
5.
Fever
6.
Weight loss
7.
Anemia
8.
Abnormal gross findings on flexible
sigmoidoscopy
Physical examination should be normal in IBS patients. If
history is consistent with Rome III criteria with no alarm features (see list
above), and no family history of IBS or colorectal cancer, then limited
investigations are required. The investigations aim to rule out diseases which
mimic IBS (see list below), especially coeliac disease and inflammatory bowel
disease; investigations can be limited to CBC, inflammatory markers (ESR, CRP),
and coeliac serology. If available, fecal calprotectin is likely more reliable
test to rule out inflammatory bowel disease. TSH and stool cultures can be
considered based on clinical circumstances. Consider colonoscopy if alarm
features present, family history of IBD, or age > 50 years.
IBS mimickers:
1.
Enteric infections e.g. Giardia
2.
Lactose intolerance (watch for osmotic ion gap)
3.
Crohn’s disease
4.
Coeliac disease
5.
Drug-induced (e.g. laxative)
6.
Diet-induced (e.g. caffeine)
Treatment includes reassurance, explanation, and support for
the patient; aim for realistic goals. Lifestyle changes include relaxation
therapy, biofeedback, hypnosis, stress reduction, and exercise. A diet that is
low in fat and high in fiber can help with symptoms such as pain, bloating, and
irregular bowel movements—of these, pain is most difficult to control. No
therapeutic agent is consistently effective for IBS; so all medications are to
treat symptoms as necessary.
Symptom-guided treatment
·
Pain predominant
o
Antispasmodic medication (such as hyoscine,
pinaverium, trimebutine) before meals (low evidence).
o
Tricyclic antidepressants, selective serotonin
reuptake inhibitors (moderate evidence).
·
IBS with diarrhea
o
Loperamide (Imodium)
o
Diphenoxylate (Lomotil)
o
Cholestyramine
·
IBS with constipation
o
Linaclotide
o
Osmotic or other laxative
80% of patients will improve over time, despite intermittent
episodes of symptoms. Most will have normal life expectancy.
