| |
In favor |
Against |
| Infection |
Sprue
is epidemic and spreads in certain geographic locations, especially
during the hot, dry season preceding the rainy season. Affected
people in the nontropics have a history of having lived in or passed
through endemic areas. Fever is often present at the onset of the
disease. There is an increase in the toxins of gram-negative bacterial
organisms and an occasional increase in bacterial colony counts.
Acute enteritis may precipitate sprue. There is an increase in inflammatory
cells in the lamina propria with variable edema. The clinical response
to tetracycline is good, and the disease can be cured, with restoration
of the normal histology of the small bowel mucosa. |
Stool and blood cultures
have not shown any organism. No antigen or antibody has been found.
Electron microscopy has identified no virus. Volunteers who ingested
algae demonstrated different clinical and biochemical findings. |
| |
|
|
| Allergy |
There is an increase in
eosinophils in the lamina propria. There is an increased incidence
and susceptibility following pregnancy and/or bacillary dysentery.
There is a close resemblance of the clinical, biochemical, radiological,
and histological presentation to the nontropical sprue of infants,
to celiac disease, and to the idiopathic steatorrhea of adults caused
by gluten sensitivity. |
No antibodies have been
found. Inflammatory cells are also seen in the lamina propria. Severe
mucosal change (subtotal villous atrophy)is seen in nearly 90% of
patients with celiac disease and steatorrhea caused by gluten sensitivity,
but in only 5%-10% of patients with sprue. There is a difference
in therapeutic response. Tropical sprue does not respond to a gluten
free diet; antibiotics do not affect gluten enteropathy. |
| |
|
|
| Failure
of mucosal maturation and deficient absorption of folic acid |
Normally
the entire mucosal epithelium of the small bowel is regenerated
every 48-72 hours. The mature surface epithelium is shed and replaced
by the new; this is a continuous process. From the crypts of Lieberkühn,
where the cells are cuboidal with large rounded nuclei, the cells
migrate up the microvilli normally, but in tropical sprue fail to
become columnar with elongated nuclei: the cytoplasm still contains
basophilic granules. This failure of maturation affects absorption,
especially of folic acid. Treatment with folic acid restores the
ability of the mucosa to mature and also reverses the megaloblastic
anemia. |
The disease
is not caused by primary folic acid deficiency. |
| |
|
|
| Deficiency of absorption
due to defective biosynthesis of intrinsic factor |
The clinical and radiological
pictures are similar. |
There is a good response
to treatment with folic acid, which is not an intrinsic factor. |
| |
|
|
| Vitamin B deficiency |
The megaloblastic anemia
is similar. |
The clinical picture of
vitamin B deficiency and pellagra is different. Vitamin B deficiency
is common in Africa and yet tropical sprue is almost unknown there. |
| |
|
|
| Endocrine deficiency |
There is good response
to cortisone. Low serum calcium, magnesium, sodium, and chloride
are seen in the late stages. |
No evidence of primary
endocrine deficiency has been found. |
| |
|
|
| Faulty fat absorption |
There is an increase in free fatty acids in the
intestines. There is excess absorption of unsaturated fatty acids
and poor absorption of saturated fatty acids. The disease appeared
in Hong Kong after refrigerators were introduced and more unsaturated
fatty acids began to be used in the diet.
|
The intestinal enzymes
are normal. There is normal splitting of triglycerides. |
| |
|
|
| Neurovascular
compromise |
Irradiation
of the vascular plexus of the small bowel produces a sprue-like
picture clinically, radiologically, and histologically. A sprue-like
picture can be seen in Goodpasture's syndrome, nephrosis, polyarteritis,
and other conditions in which there is vascular compromise of the
mesenteric plexus. The basic lesion may be the damage to the fine
vascular bed of the bowel wall and autonomic nerves in Auerbach's
and Meissner's plexi with disruption of their normal function. The
eventual atrophy of the entire bowel wall is consistent with vascular
deficiency. Many of the radiological findings in tropical sprue
could be explained in this way. |
|
| |
|
|
| Lymphatic
disruption |
The clinical
and radiological presentations of certain diffuse lymphomas and
Whipple's disease resemble sprue. |
No nodal involvement
is seen. There is no persistent edema in sprue. |
| |
|
|
| Alteration
of intestinal bacterial flora |
Improvement
by treatment with antibiotics is noted. |
No consistent
alteration of intestinal bacteria has been documented. |
| |
|
|
| Autoimmune
disease |
|
There is no
change in immunoglobulins. There is no increase in lymphocytes. |
