Immunhistochemische Untersuchung des Fruktosetransporters GLUT5 an Patienten mit einer Fruktosemalabsorption

Background: Patients with abdominal symptoms are frequently diagnosed with Fructose malabsorption (FM), but mechanisms behind recurrent symptoms are not fully understood. Fructose is absorbed by monosaccharide transporters located in the brush border of the human small intestine. The aim of this study was to investigate the histoanatomical distribution of the main fructose transporter GLUT5. Materials and methods: We studied 223 patients diagnosed with FM by a hydrogen breath test and grouped them according to their response to a fructose-free diet. The control group were 42 healthy individuals and 29 patients with coeliac disease (CD). The fructose breath test was done with 50g fructose and FM was defined as an increase in H2 of 20 ppm. The expression of GLUT5 in duodenal biopsy specimens was studied by immunohistochemistry. The Kruskal-Wallis-test and Mann-Whitney U-test were used to carry out the statistical analysis. Results: The histoanatomical expression pattern of GLUT5 did not differ significantly between those patients with FM who responded completely to a fructose-free diet (n=183) and healthy individuals (n=42); nor did it correlate to H2 production measured in fructose breath testing. In patients with FM, the GLUT5 expression pattern did not differ between those individuals responding to a fructose-free diet and those not. However, GLUT5 expression pattern was significantly different in patients with CD (n=29) compared to patients with FM and to healthy individuals (p=0.009). Conclusion: Changes in GLUT5 expression pattern may not be related to adult patients with FM. However, in secondary malabsorption, a decreased GLUT5 expression was found. Further investigation is needed to understand the essential factors in FM and the influence on functional gastrointestinal disorders.