Increased gastrointestinal (GI) permeability is associated with more than 40 different GI conditions, including irritable bowel syndrome (IBS). In a recent study, NINR researchers evaluated a novel non-invasive approach for measuring altered permeability in both the upper and lower GI tracts of IBS patients. Results demonstrate the potential for using a single four-probe GI permeability solution as a clinical measurement tool.

About 1 in 6 people in the U.S. have symptoms of IBS, according to the National Library of Medicine. The disorder leads to abdominal pain and cramping, changes in bowel movements, and other symptoms, which can range from mild to severe. IBS is also associated with altered GI permeability, which can affect the clinical course of the disease and influence the success of an intervention or treatment. However, detecting and measuring GI alterations still presents a challenge in clinical settings.

A team led by Dr. Wendy Henderson, chief of NINR’s Division of Intramural Research’s Digestive Disorders Unit, set out to evaluate the efficacy of a novel approach for measuring altered permeability at different regions along the GI tract in IBS patients. After an overnight fast, participants, which included both IBS patients and matched healthy controls, drank a permeability test solution containing sucrose, lactulose, mannitol, and sucralose. These chemicals represent four sugar probes, which absorb at different rates and places in the stomach, small intestine, and colon.

Fig. 1. Standard sugar test solution is used to determine permeability throughout the GI tract. Gastric absorption of sucrose occurs between 0 and 3 h after solution ingestion. Lactulose is absorbed in the small intestine between 3 and 5 h and mannitol is used to standardize surface area. Colonic permeability is typically assessed by sucralose excretion of  5 h.
Fig. 1. Standard sugar test solution is used to determine permeability throughout the GI tract. Gastric absorption of sucrose occurs between 0 and 3 h after solution ingestion. Lactulose is absorbed in the small intestine between 3 and 5 h and mannitol is used to standardize surface area. Colonic permeability is typically assessed by sucralose excretion of ≥ 5 h.

During the five hours after participants drank the test solution, researchers collected urine samples. They then measured the recovery of the probes in the urine using a liquid chromatography mass spectrometry-based method. The researchers found altered colonic permeability in the lower GI tract regions of patients with clinically defined IBS. They also demonstrated that gastric and small intestinal permeability profiles in the upper GI tract regions did not significantly differ between IBS patients and healthy controls.

“In this study, we explored the potential of using a four-probe test solution to identify and measure altered permeability in the GI tract of patients who are suffering from conditions such as IBS,” Dr. Henderson explained. “We hope the ability to fully characterize an individual’s permeability profile along the entire GI tract using our novel method for analysis will help other clinicians trying to make an informed diagnosis. It may also help them choose more effective, individually tailored treatments.”

She also noted: “The validation of this method was also critical to the overarching goal of our research, to understand IBS symptoms as they may relate to multiple body systems.”

Results from this study were recently published in the journal of Clinica Chimica Acta. To read the abstract, visit http://www.ncbi.nlm.nih.gov/pubmed/23328210.