When your kidneys stop working suddenly (and usually over a short period of time), it is called an Acute Kidney Injury (AKI). AKI is also sometimes called acute kidney failure or acute renal failure. It is very serious and requires immediate treatment.
AKI is often reversible when diagnosed early and treated quickly. If your kidneys were healthy before the event that caused the injury and you are treated for AKI right away, your kidneys may work normally or almost normally after treatment. However, some people have lasting kidney damage after AKI which then leads to chronic kidney disease.
Here is Dr. Hector Diaz-Rodriguez in a short presentation about Acute Kidney Injury