At one time, researchers thought that stress and
diet caused Crohn’s disease. Now researchers know
that these are not factors, although both stress and diet
can worsen symptoms in people who already have the
disease.
What researchers do know is that Crohn’s
disease is caused by an inappropriate immune system
reaction that affects cells in the digestive tract. Beyond
that, the reasons why some people develop the disease
are not clear.
There is almost certainly an inherited component
that predisposes some people to the disease. Individuals
who are blood relatives of a parent, sibling, or child
with Crohn’s disease are 30 times more likely to
develop the disease than the general population.
Scientists
believe multiple genes are involved in development
of the disease. However, more than genetics
determines who gets Crohn’s disease, because only
about 44% of identical twins both develop the disease.
Researchers have found several mutated (altered)
genes in many, but not all, people who have Crohn’s
disease but do not yet have a clear understanding of
what these genes do.
Current thinking is that interplay between genes,
the environment, the individual’s health, and body
chemistry affect who develops Crohn’s disease.
When foreign materials (antigens) enter the body, the
immune system produces antibodies, which are proteins
that neutralize the foreign invader.
One theory
about Crohn’s disease is that some foreign organism
or material stimulates an immune system response in
the digestive system, and then through an error in
genetic control, the response cannot be ‘‘turned off.’’
A second theory suggests that the cells of the immune
system mistake good bacteria, food, or some other
substance that is normally present in the digestive
tract and make antibodies against this material as if
it were a foreign substance.
Either way, an inappropriate
immune system response occurs that appears to
be the root cause for the symptoms people with
Crohn’s disease experience.
Symptoms of Crohn’s disease vary, depending on
the location of the damaged cells and the length of
time the individual has had the disease.
Symptoms can
be mild or severe. They can develop suddenly or gradually,
and they may improve or even disappear, and
then worsen many times throughout an individual’s
life. In general, symptoms can be divided into those that affect the digestive tract and those that affect the
rest of the body.
The most common symptoms that affect the
digestive tract are:
-chronic diarrhea, the most common symptom
-abdominal pain or cramps, often in the lower right
portion of the abdomen
-rectal bleeding
-blood in the stool, black tarry stool
-ulcers in the digestive tract, usually the in the intestine
-fistulas, or holes in the intestine that connect the intestine
to other parts of the body such as the bladder,
stomach, vagina, or another section of bowel
-nausea and vomiting , usually from Crohn’s disease
in the stomach
-abscesses, fistulas, and ulcers around the anus, usually
from Crohn’s disease in the colon. This occurs in
about 45% of patients
-constipation, usually after many years when the
bowel has thickened and the diameter of the intestine
has narrowed
Symptoms of Crohn’s disease also appear in other
systems in the body. Some are the result of infection
when fistulas develop. Others come from poor absorption
of nutrients in the intestine over a long period.
Some symptoms that occur outside the digestive tract
include:
-persistent low-grade fever
-loss of appetite and weight loss
-fatigue
-anemia from blood loss and/or poor iron absorption
-skin infections
-eye infections
-arthritis and sore joints, usually in the large joints
such as the knees or hip
-osteoporosis from poor calcium and vitamin D
absorption
-poor blood clotting from inadequate vitamin K
absorption
-stunted growth in children
-delayed puberty
