What is the definition of chronic kidney disease according to the National Kidney Foundation and the International Kidney Disease Improving Global Outcomes?

Chronic kidney disease is a broad syndrome that encompasses various disorders that result in abnormal renal structure, function, and/or filtration rate.
The stages 1 and 2 reflect the preservation of a glomerular filtration rate greater than 60 mL/min/1.73 m2 but abnormally high albuminuria.
The stages 3 to 5 manifest a progressively worse glomerular filtration rate.