Differential sugar absorption as a marker for adaptation in short bowel syndrome

PURPOSE: There are no reliable monitoring methods for following up with patients with short bowel syndrome (SBS). This study examines the use of inert sugar markers (mannitol and lactulose) as indicators of the surface area increases occurring with adaptation. METHODS: Juvenile male rats underwent either transection with intestinal reanastomosis or resection with removal of the proximal 90% of the small bowel, leaving 10 cm of terminal ileum (n = 8 in each group). Animals were studied in vivo, measuring absorption of mannitol and lactulose on day 7, 14, and 28 and killed with the representative histological samples taken on day 7, 14, and 28. RESULTS: Resected animals showed significant increases in intestinal length (initial bowel length 10 cm, final length 17.8 +/- 1.4 cm, while transected showed no significant changes (101 +/- 2 cm): resection also increased intestinal circumference (initial circumference 0.5 cm +/- 0.1 cm, final circumference 1.1 cm +/- 0.2 cm in resected animals, while transected animals remained unchanged). Resected animals also showed significant increases in villus height (0.7 +/- 0.06 mm initially, 0.9 +/- 0.09 mm at day 28), and but a decrease in villus density (116 +/- 20 villi/mm2 initially, 78 +/- 20 villi/mm2 at day 28), again controls showed no changes. This resulted in a significant increase in intestinal surface area in resected animals over the study; surface area initially calculated at 640 +/- 80 cm2 increasing to 1,440 +/- 360 cm2, while controls showed no significant change in surface area. There was also an increase in mannitol absorption, which went from 1.8 +/- 0.6% on day 7 to 2.56 +/- 0.6% on day 28 in resected animals, while permeability actually decreased over time. (All data mean +/- SD, with P<.05 by Student's t test). Mannitol absorption correlated well with intestinal surface area (R2 = 0.82). CONCLUSION: These results suggest that inert sugar markers, such as lactulose and mannitol, may be useful in following adaptation in patients who have short bowel syndrome.