This test measures the ability of two sugar molecules, lactulose and mannitol, to permeate the intestinal epithelial barrier. Ordinarily, mannitol is efficiently absorbed but lactulose, a larger molecule, is not. This test can help to identify malabsorption and “leaky gut” syndrome (abnormal intestinal permeability), which is often associated with inflammation specifically in the gastrointestinal tract. This test requires a baseline urine collection followed by a six-hour timed urine collection after ingesting a lactulose and mannitol solution. This test is useful for Gastrointestinal Symptoms Food Sensitivities Inflammation Malabsorption Nutritional Deficiencies *Cost includes purchasing lab ONLY, protocol and interpretation sold separately**