Master the board step 3

Master the Boards: USMLE Step 3
Celiac Disease (Gluten-Sensitive Enteropathy)
Celiac disease can also present with malabsorption of iron and microcytic
anemia. This does not happen with pancreatic insufficiency, since pancreatic
enzymes are not necessary for iron absorption. Folate malabsorption also
occurs from destruction of villi. Celiac disease is associated with a vesicular skin
lesion not present on mucosal surfaces. This is called dermatitis herpetiformis.
Diagnostic Testing
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Best initial test: Antigliadin, antiendomysial, and antitissue transglutaminase
antibodies
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Most accurate test: Small bowel biopsy
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D-xylose testing is abnormal in celiac disease, Whipple disease, and tropical
sprue, because the villous lining is destroyed and D-xylose cannot be
absorbed. However, this test is rarely necessary, because the specific antibody
tests eliminate the need for it.
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Bowel biopsy is always necessary for celiac disease, even if the diagnosis is
confirmed with antibody testing, to exclude bowel wall lymphoma.
Treatment
Eliminate wheat, oats, rye, and barley from the diet. It may take several weeks
for symptoms to resolve. Beer, whiskey, and most vodkas are derived from
wheat. Wine is okay.
Tropical Sprue
This presents in the same way as celiac disease. There will be a history of the
patient being in the tropics. The serologic tests, such as antitissue transglutaminase,
will be negative.
The most accurate test is a small bowel biopsy showing microorganisms.
Treatment consists of doxycycline or trimethoprim/sulfamethoxazole (TMP/
SMX) for 3–6 months.
Whipple Disease
Whipple disease has several additional findings on presentation, such as the
following:
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Arthralgia
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Neurological abnormalities
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Ocular findings
Diagnostic Testing
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Most accurate test: Small bowel biopsy showing PAS positive organisms
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An alternate test is PCR of the stool for Tropheryma whippelii.
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