Research overview: IRIS staging of feline chronic kidney disease

The International Renal Interest Society (IRIS) staging system standardized how feline chronic kidney disease (CKD) is classified, using blood creatinine, and later SDMA, to define stages, with substaging by urine protein and blood pressure. This framework brought consistency to diagnosis, prognosis, and treatment decisions across practices and studies, enabling stage-appropriate interventions such as dietary therapy, phosphorus control, and hypertension management. This overview synthesizes the staging literature and guidelines rather than one citation, describing how the system links measurable biomarkers to clinical action, why substaging on proteinuria and blood pressure refines prognosis, and how widespread adoption of IRIS staging improved the care of one of the most common and important diseases of older cats.