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Copyright (c) 1994 Scientific American Medicine.
Diseases of the Small Intestine
Celiac Sprue
Celiac disease of childhood and nontropical sprue
(gluten-sensitive enteropathy) in adults define the spectrum
of the celiac sprue syndrome. (ref 25) This disorder has
been popularized by writings of experts on intestinal
histology, but physicians rarely encounter it in their
practices. Only three to six cases a year are seen at
Stanford University Hospital, and several of these patients
have had sprue for many years. Perhaps this observation
reflects the fact that the prevalence of clinically manifest
celiac sprue appears to have decreased during the past 10 to
15 years. (ref 26)
Weight loss occurs in virtually all patients with celiac
sprue, even though the patient usually has an adequate
appetite; anorexia appears several months to a
year later. Three quarters of all patients report
abdominal distention, a sensation of bloating,
and associated fatigue; 50 percent have anemia,
usually of the megaloblastic type, attributable to folic
acid deficiency. Although usually considered to be an
important symptom, frank diarrhea is a major complaint in
less than half of adult patients; it is usually intermittent
and lasts less than six months. (ref 27) A small percentage
of patients complain of nausea, tetany, cutaneous bleeding,
glossitis, or psychiatric symptoms. All patients have an
increase in the volume of stool, and there is usually an
increase in stool frequency early in the course of the
disease. Associated findings include a history of celiac
disease as a child or a family history of celiac sprue. In
fact, 25 percent of patients report such a family history.
Celiac disease is often seen in females of short stature (a
mean height of 150 cm, compared with 160 cm in the average
population). Among celiac sprue patients, there is also an
increased prevalence of blood type O and histocompatibility
antigen HLA-B8 or DRw3. The presence
of a particular HLA genotype in an individual is not
sufficient in itself to cause celiac sprue. Siblings of
patients with celiac sprue who share the HLA-B8 or DRw3
antigen have a low prevalence (about eight percent) of
sprue. (ref 28, 29) Indeed, ingestion of gluten by normal
monozygotic twins and siblings with HLA haplotypes identical
to those of affected patients does not produce altered
intestinal histology or malabsorption. This finding
indicates that other factors in addition to a genetic
predisposition and ingestion of gluten are required for
expression of this small intestine disease. (ref 30)
In recent years, patients have been identified earlier in
the course of the disease. (ref 31) Fatigue or a mild anemia
may be the initial subtle abnormality. Patients with a
history that suggests small intestine malabsorption should
undergo a quantitative fecal fat analysis, small intestine
biopsy, xylose absorption test, and small intestine x-ray
(see above). Small intestine histology is distinctly
abnormal, with marked reduction
in the villus height or total flattening of villi [see
Figure 3].
Therapy is directed at removal of gluten from the diet; the
-gliadin fraction of gluten is responsible for the clinical
syndrome. The main sources of gluten are wheat, barley,
oats, and rye. Therefore, foods that must be avoided are
bread and most flours made from these grains. Beer, ale,
vodka, and whiskey may contain significant amounts of gluten
and should also be avoided. Easily overlooked sources of
gluten include ice cream and other dairy products that may
have had gluten added in processing, communion wafers,
chewing gum, (ref 32) and drugs that contain gluten as an
excipient. (ref 33) Within these limitations, patients may
still have a balanced diet containing milk, cheese, eggs,
meat, fish, poultry, yellow and green vegetables, potatoes,
nuts, and chocolate. Substitution of rice, corn cereals,
potato flour, and other starches for foods that contain the
offending gluten makes it relatively easy for these patients
to maintain adequate nutrition. Response to gluten exclusion
is required for
verification of the diagnosis, and the vast majority of
patients with celiac sprue do respond relatively quickly.
After one to three days of gluten exclusion, 30 percent of
patients show marked improvement, and after one week to a
month, another 50 percent improve. For 10 percent of
patients, however, remission does not occur for one to two
months, and another 10 percent may not show improvement for
up to two years after gluten has been excluded from the
diet.
In patients who fail to respond to complete gluten
restriction after three months, a trial of
adrenocorticotropic hormone (ACTH) (20 to 40 U/day) or
prednisone (20 to 40 mg/day) may be necessary.
There have been reports of celiac sprue associated with
inflammatory bowel disease in the small intestine or colon.
(ref 34, 35) Ulcerative colitis or Crohn's disease may
precede or follow celiac sprue by months or even years.
Because symptoms of inflammatory bowel disease may mimic
those of celiac sprue, it is
worth noting that the two diseases can coexist.
The most important complications of celiac sprue are the
development of ulcerations (ref 36) and malignant disorders
(ref 37, 38) of the small intestine. The risk of an
intestinal malignant tumor appears to increase with the
duration of the disease, and careful adherence to a
gluten-free diet has not been shown to decrease that risk.
Nonmalignant ulcerations tend to develop in patients with
severe disease that is only partially responsive to gluten
exclusion. Although prednisone has been used, surgical
excision is frequently necessary, and patients with mucosal
ulcerations are often less responsive to dietary restriction
of gluten or to prednisone therapy than those without
ulcers. Primary small intestine malignant tumors develop in
15 to 20 percent of celiac sprue patients; about half of
those tumors are histiocytic lymphomas, and the other half
are adenocarcinomas. The incidence of carcinoma of the small
intestine in these patients is about 100-fold greater than
that in the general population. Any patient
with celiac sprue who becomes inexplicably refractory to
gluten exclusion should be evaluated for a possible small
intestine malignant disorder.
Dermatitis Herpetiformis and Celiac Sprue
Dermatitis herpetiformis usually occurs in association with
celiac sprue. The vast majority of patients who have
dermatitis herpetiformis can be shown to have flat jejunal
villi, but less than five percent of these patients show the
other typical signs of celiac sprue. (ref 39) The skin
lesions of dermatitis herpetiformis are intensely pruritic
blisters that appear on the shoulders, buttocks, knees, and
elbows. Skin biopsy reveals immunoglobulin A (IgA) deposits
in the involved lesions. A gluten-free diet may lessen the
severity of the skin lesions in some patients. (ref 39) Skin
lesions respond dramatically to therapy with dapsone but
commonly recur if drug therapy is not maintained. The
intestinal lesion does not appear to respond to
dapsone but usually improves when gluten is eliminated from
the diet. Therefore, it is assumed that most patients with
dermatitis herpetiformis have the celiac sprue syndrome.
Tropical Sprue
Individuals living in tropical regions, including India,
Puerto Rico, and Vietnam, appear to be at risk for tropical
sprue, which consists of partial flattening of intestinal
villi [see Figure 4] and subepithelial lymphocytic
infiltration and is associated with malabsorption, weight
loss, severe fatigue, and marked megaloblastic anemia. (ref
40) Anorexia is usually more severe than in celiac sprue and
may be even more important than malabsorption in causing
rapid weight loss. (ref 41) Tropical sprue appears to be
linked to infection with an undefined agent. The syndrome
develops in 10 percent of United States Army recruits
stationed in Puerto Rico. Clinical symptoms may not be
manifest in some cases until several months after the
individual has returned
from an endemic area. Seventy-five percent of patients
respond within two weeks to folic acid therapy (5 mg p.o.,
t.i.d., for one week, followed by a maintenance dosage of 1
mg t.i.d). Both the anemia and the small intestine
malabsorption are ameliorated by this therapy. One quarter
of patients with tropical sprue, however, require antibiotic
therapy (tetracycline, 500 mg q.i.d., or ampicillin, 500 mg
q.i.d., for two to four weeks or longer) to achieve a
remission.
Several features of tropical sprue distinguish it from
celiac sprue: the histologic appearance of the intestinal
lesion, the exposure of patients to certain geographic
locations, the severity of the megaloblastic anemia
(hematocrits of 20 to 25 are not uncommon in tropical
sprue), and the dramatic response to folic acid or
antibiotics, which are not effective in celiac sprue.
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