In vivo measurement of intestinal absorption using 3-0 methylglucose in short bowel syndrome.

PURPOSE: The management of patients with short bowel syndrome is complicated by the paucity of methods to assess in vivo the absorptive capacity of the remaining bowel. The purpose of this experiment was to assess the feasibility of using urinary recovery of 3-0 methylglucose (3-0 MG) as a quantitative measure of carbohydrate absorptive capacity, comparing it with in vivo absorption and in vitro glucose transport studies. METHODS: Male Sprague Dawley rats underwent either a 90% proximal small bowel resection or sham resection (n = 8 in each group). Animals were pair fed, weighed, and followed up for 14 days. A 3-day balance study was done, measuring feed intake and fecal output for percentages of fat and energy absorption. Animals were gavaged with 3-0 MG/Mannitol solution, and 4-hour urinary recovery of sugars was assessed using high-performance liquid chromatography (HPLC). On different days these studies were repeated with increasing amounts of added normal glucose (1 mol/L, 1.25 mol/L, and 1.5 mol/L) in the gavage solution given to compete for 3-0 MG transport, and thus increase the "sensitivity" of the test. Animals were then killed, and sections of intestine taken for in vitro assessment of glucose transport using radiolabeled 3-0 MG in Ussing chambers. RESULTS: Total energy, carbohydrate, and fat absorption all were reduced significantly in the resected animals, as was 3-0 MG urinary recovery (62.9 +/- 10.5%) in controls versus (35.8 +/- 17.5%) in resected animals (P <.05). 3-0 MG urinary recovery correlated well with dietary carbohydrate absorption (r = 0.74), and with Ussing chamber measures of glucose flux (r = 0.97). Adding exogenous glucose to the test solution to "compete" for 3-0 MG transport sites did not improve sensitivity. CONCLUSIONS: These results show that 3-0 MG is useful in measuring nutrient absorption capacity in rats after massive small bowel resection. Further studies to validate these methods in human patients with short bowel syndrome are suggested.