Tropical Sprue Workup

Updated: Dec 15, 2014
  • Author: Rohan C Clarke, MD; Chief Editor: Julian Katz, MD  more...
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Laboratory Studies

See the list below:

  • Clinical presentation, including diarrhea, malabsorption of nutrients, and anemia workup, influences the extent of diagnostic tests. Findings of steatorrhea, mucosal malabsorption of 2 substances (eg, fat, D-xylose), and villous atrophy (demonstrated by means of biopsy) are adequate to make a diagnosis. Response to treatment is considered by some to be the conclusive evidence that confirms the diagnosis.

  • CBC count: This shows megaloblastic anemia associated with reduced folate and vitamin B-12 levels in as many as 60% of patients.

  • Blood chemistry test: This includes potassium, calcium, magnesium, phosphate, albumin, cholesterol, and iron studies.

  • Stool collection test

    • This measures fat content over 72 hours on a diet of 80-100 g of fat.

    • A result of more than 6 g in 24 hours is abnormal (positive for fat malabsorption). Fatty stools are usually observed when the stool fat content is 15 g or more.

  • D-Xylose absorption test

    • For this study, 25 g D-xylose is administered orally.

    • In well-hydrated patients with normal renal function, abnormal results (ie, positive for mucosal malabsorption) include a 5-hour urine collection of less than 4 g and a 1-hour serum collection of less than 20 mg/dL.


Imaging Studies

See the list below:

  • A barium swallow and follow-through may reveal increased caliber and thickening of mucosal folds or flocculation and segmentation of barium, depending on the type of barium used.

  • Use of esophagoduodenoscopy may reveal subtle or dramatic mucosal changes, [7] as seen in the following images.

    Endoscopic views of unsuspected celiac disease. A: Endoscopic views of unsuspected celiac disease. A: Absent duodenal folds. B: Mucosal fissures and scalloped folds. C: Scalloped fold.

Other Tests

Another possible tool to determine gut health may be a noninvasive marker. In a small Australian study, Ritchie et al reported a novel use of of13 C-sucrose breath test in 36 Aboriginal and non-Aboriginal children to measure enterocyte sucrase activity as a marker of small intestinal villus integrity and function. [8] The investigators simultaneously performed intestinal permeability measurements with the lactulose/rhamnose (L/R) ratio on a timed 90-minute blood test with the13 C-sucrose breath test.

Findings included a significantly decreased absorption capacity in Aboriginal children with acute diarrhea (mean 1.9%; cumulative percentage calculated of dose recovered at 90 min) relative to Aboriginal children without diarrhea (4.1%) or non-Aboriginal children (6.1%). [8] The mean L/R ratio in the Aboriginal children with diarrhea was 31.8, whereas the nondiarrheal Aboriginal children's was 11.4.

Ritchie et al noted a significant inverse correlation between the13 C-sucrose breath test and the L/R ratio and concluded the breath test discrimated "among Aboriginal children with diarrhea, asymptomatic Aboriginal children with an underlying environmental enteropathy, and healthy non-Aboriginal controls." [8] The investigators believe the13 C-sucrose breath test "provides a noninvasive, easy-to-use, integrated marker of the absorptive capacity and integrity of the small intestine and could be a valuable tool in evaluating the efficacy of interventions aimed at improving gut health." [8]



See the list below:

  • Jejunal biopsy

    • Mild villous atrophy

    • Increased villous crypts and mononuclear cellular infiltrates, enlarged epithelial cells, and large nuclei caused by folate and/or vitamin B-12 deficiency

  • Characteristic accumulation of lipid beneath the basement membrane


Histologic Findings

The following images are supportive of histopathologic findings of tropical sprue. [9]

Subtotal villous atrophy (H&E, orig. mag. ×10). Subtotal villous atrophy (H&E, orig. mag. ×10).
Tropical sprue (H&E, orig. mag. ×10). Tropical sprue (H&E, orig. mag. ×10).