Acute kidney injury (AKI) is a medical condition that affects the kidneys, usually due to a sudden drop in blood flow or damage to the kidneys themselves. There are several synonyms for AKI, including acute renal failure (ARF) and acute kidney failure, which imply that the kidneys are no longer functioning properly and that they are not able to filter waste products and excess fluids from the body as they should. Other terms used to describe this condition include acute kidney damage, acute kidney disease, and acute kidney insufficiency. Regardless of the specific terminology used, it is important to seek medical attention for AKI as soon as possible to prevent further damage to the kidneys.