PEDIATRIC DUODENAL BIOPSIES - MUCOSAL MORPHOLOGY AND GLYCOHYDROLASE EXPRESSION DO NOT CHANGE ALONG THE DUODENUM

Background: Duodenal mucosal biopsies are routinely taken for diagnosi s in children with complaints of the upper gastrointestinal tract. Sur prisingly, little is known about the usefulness of proximal duodenal v ersus distal duodenal biopsies for routine diagnostic purposes. This s tudy evaluated the comparability of proximal and distal duodenal biops ies with respect to mucosal morphology as well as glycohydrolase expre ssion as an indicator of intestinal epithelial function. Methods: Spec imens obtained in duodenal endoscopic biopsies from 64 children, rangi ng in age from 3 months to 18 years with normal or affected mucosa, we re studied. Biopsies were performed in anatomically defined regions in the bulbus duodeni (the very proximal part of the duodenum) and dista lly of the papilla of Vater (distal of the pancreatic duct). Biopsy sp ecimens were paraformaldehyde-fixed for histologic examination and imm unohistochemical evaluation or were homogenized to isolate RNA. Crypt/ villus morphology was assessed as is routinely determined by pathologi sts. In addition, several aspects of lactase and sucrase-isomaltase ex pression as paradigms of intestinal brush border enzymes were assessed : localization at the cellular level, semiquantitative immunohistochem istry, and quantitative measurement of the messenger RNA levels of the respective brush border glycohydrolases. Results: As anticipated, the re was a wide interpatient variation in mucosal morphology and express ion of lactase and sucrase-isomaltase. Nonetheless, the consistent fin ding was that in each patient, measurements of morphology and lactase and sucrase-isomaltase gene expression were very similar between sampl es obtained in the proximal and distal biopsies. Conclusions: Biopsies performed in either location in the duodenum are equally suitable for diagnostic workup of patients suspected of mucosal abnormalities affe cting morphology or small intestinal brush border glycohydrolase activ ities.