INFLAMMATORY BOWEL DISEASE
Inflammatory bowel disease
(IBD) is a term comprising 2 disease entities: Crohn disease (CD) and ulcerative colitis (UC).
They can be discussed simultaneously because of the large degree of overlap in terms of
presentation, testing, and treatment. Both CD and UC are idiopathic disorders of the bowel associated with diarrhea, bleeding, weight loss, fever, and abdominal
pain. Both are most accurately diagnosed with endoscopy and sometimes with barium stud- ies, “string sign” on small bowel follow through after barium meal in CD, and both are treated with
anti-inflammatory medications, such as mesalamine, azathioprine, and
6-mercaptopu- rine (6MP). Steroids
are used for acute exacerbations of both diseases.
Clinical Presentation. IBD presents with fever, diarrhea, weight
loss, and, occasionally, abdomi- nal pain and bleeding. The extraintestinal manifestations of IBD are episcleritis, scleritis and iri- tis,
sclerosing cholangitis, joint pains, and skin manifestations, such as pyoderma gangrenosum or erythema nodosum.
Crohn disease is more likely
to be associated with a palpable abdominal mass because CD has
granulomas in the bowel wall that are transmural in nature. This
can lead to the different loops of bowel being
inflamed and sticking
together, forming a mass. The abdominal masses
of CD can be palpated and
cause pain. CD is not necessarily continuous, and one hallmark of the disorder is that there are “skip lesions,”
or areas
of normal tissue
in between
the areas
of disease.
UC is
limited exclusively to the large bowel. It is exclusively a mucosal disease,
and although it can cause bleeding, it does not result in fistula formation. UC
has no skip lesions, no fistula formation, and no oral or perianal involvement.
UC is more likely to cause bloody diarrhea.
Note
Sclerosing cholangitis does not correlate to disease
activity.
Both
forms of IBD can lead to colon cancer after 8 to 10 years of involvement of the
colon. If the CD does not result in colonic involvement, then it will not lead
to cancer. Complications of Crohn
disease are calcium oxalate kidney stones, diarrhea, and cholesterol gallstones.
Diagnosis. IBD is diagnosed with endoscopy
and sometimes with barium studies. (CD can
result in deficiency of vitamin B12, calcium, vitamin K,
and iron because of malabsorption.) Anti–Saccharomyces cerevisiae antibodies (ASCA)
are associated with CD, and antineutrophil
cytoplasmic antibody (ANCA) is associated
with UC. If a patient is ASCA positive
and ANCA
negative, then he
or she has a >90% chance of
having CD. If the patient is ASCA negative and
ANCA positive, there is a >90% chance of having UC.
Prothrombin time may be prolonged in CD because
of vitamin K malabsorption. Kidney
stones form more often in CD because the fat malabsorption results in a
low calcium level and an increased absorption of oxalate, which
forms kidney stones.
Treatment. Mesalamine derivatives are the mainstay of therapy
for IBD in all of its forms. Pentasa is a form of mesalamine released in both
the upper and lower bowel; hence, it is used in CD. Asacol
is a form of mesalamine released
in the large bowel, and it is most useful
for UC. Rowasa is used
exclusively for rectal disease. Sulfasalazine was used in the past for the same
effect. The difficulty with sulfasalazine is that the high load of sulfa
delivered causes a number of
adverse effects, such as rash, hemolysis, and allergic interstitial nephritis.
Sulfasalazine also causes reversible infertility in men and leukopenia by its
sulfapyridine group.
Acute exacerbations of
IBD are treated with high-dose steroids. Budesonide is a form of steroid that is ideal for IBD. It has a strong
local effect when used orally, but is largely
cleared by the liver in
a first-pass effect.
This limits the amount of systemic
toxicity. Azathioprine and 6-mercaptopu- rine are associated with drug-induced pancreatitis, but are still used on a long-term
basis to try to
keep patients off steroids. Ciprofloxacin and metronidazole are used for CD in those with perianal disease. Infliximab is used
for CD in those who
form fistulae or have disease refractory to the other
forms
of
therapy. There has
been
re-activation of
tuberculosis with
infliximab, and
it
is
important to
test
for
latent tuberculosis with
a
purified
protein derivative (PPD)
prior
to
treatment.
If
the PPD
is
positive, then
patients
should
receive
isoniazid.
The
most
common side
effect
of
infliximab
is
arthralgias.
Balsalazide
and
olsalazine
are other
forms
of
mesalamine
that
are only
active in
the colon and
are used
occasionally.
Surgery is curative in UC; almost 60% of patients will require
surgery within
5 years after diagnosis due to refractory symptoms or severe disease.
Surgery is not very effective in CD and disease
tends to reoccur at the site of
anastomosis.
