What is acute kidney injury (AKI)?

Acute kidney injury (AKI) is best described as a sudden decrease in kidney function. This condition typically occurs over hours to days and is marked by an increase in serum creatinine, a decrease in urine output, or both. The acute nature of the injury differentiates it from chronic kidney disease, where the loss of kidney function is more gradual and typically irreversible.

The suddenness of AKI can result from various causes, such as dehydration, obstruction of the urinary tract, medication effects, or direct damage to the kidneys from toxins or ischemia. Recognizing AKI promptly is crucial for management, as it may be reversible if the underlying cause is addressed in a timely manner.

Other options describe conditions or processes that are inconsistent with AKI. For instance, a gradual loss of kidney function aligns more with chronic kidney disease rather than the acute nature of AKI. A permanent loss of kidney function suggests irreversible damage typically seen in end-stage renal disease, while kidney enlargement refers to a physical change that can occur due to various reasons but does not define the acute functional changes associated with AKI.