急性肾损伤(Acute kidney injury、AKI、以前称为"急性肾衰竭"(acute renal failure、ARF)、急性肾功能衰竭)，通常在7天内肾脏发展为肾功能突然损失掉。

其原因是多方面的。通常它发生是因为肾组织损坏造成的，其起因为任何病因(例如低血压)肾血流量的减少(肾缺血(ischemia))、暴露于对肾有害的物质(Nephrotoxicity)、肾发炎的过程，或阻塞尿流量的尿路阻碍。AKI诊断是基于特有的实验室研究结果上、如升高的尿素氮及肌酸酐，或肾脏不能产生足够量的尿。

Acute kidney injury (AKI), previously called acute renal failure (ARF), is an abrupt loss of kidney function that develops within 7 days.

Its causes are numerous. Generally it occurs because of damage to the kidney tissue caused by decreased renal blood flow (renal ischemia) from any cause (e.g. low blood pressure), exposure to substances harmful to the kidney, an inflammatory process in the kidney, or an obstruction of the urinary tract which impedes the flow of urine. AKI is diagnosed on the basis of characteristic laboratory findings, such as elevated blood urea nitrogen and creatinine, or inability of the kidneys to produce sufficient amounts of urine.