This study will address two specific research questions simultaneously: 1. validation of the GastroIntestinal (GI) Dysfunction score (GIDS). 2. description of epidemiology, risk factors, and management of phosphate disorders. The aim is to recruit 20 ICUs and 1500 ICU patients. Sites will recruit all consecutive adult patients to a maximum of 120 patients or a maximum recruitment period of 8 weeks, whichever comes first. Daily data collection on gastrointestinal signs and symptoms as well as phosphate values and management will be collected during ICU stay for maximum of 7 days. 28 and 90 day mortality and days free of organ support will be the main outcomes. Secondary outcomes include prevalence of hypo- and hyperphosphatemia and description of their management.