The Crossroads Between the Kidney and Gastrointestinal Disorders: Core Curriculum 2026

The kidney and gastrointestinal (GI) tract are closely linked through a bidirectional system involving complex interactions called the gut-kidney axis. Within this system, alterations in the gut microbiome can promote progression of chronic kidney disease (CKD) while uremic toxins from advanced kidney dysfunction can adversely affect intestinal health. Incretin hormones, particularly glucagon-like peptide 1 (GLP-1), play an important role in this gut-kidney signaling and will be explored here. We also examine how this physiology helps explain the connection between GI illness and IgA nephropathy, along with the kidney manifestations seen in inflammatory bowel disease. Furthermore, we will review how CKD and end-stage kidney disease increase the risk of GI disease and complicate its management, and how CKD therapies affect GI symptoms. In this AJKD Core Curriculum, we use a case-based format to illustrate the intricate interplay between the kidneys and the GI tract.