Reviewed by Rishi Desai, MD, MPH
Renal failure, also known as kidney failure or renal insufficiency, is a medical condition in which the kidneys fail to adequately filter waste products from the blood. The two main forms are acute kidney injury, which is often reversible with adequate treatment, and chronic kidney disease, which is often not reversible. In both cases, there is usually an underlying cause.
Acute kidney injury
Acute kidney injury is the abrupt loss of kidney function, resulting in the retention of urea and other nitrogenous waste products and in the dysregulation of extracellular volume and electrolytes. The term acute renal failure is now reserved for severe acute kidney injury, usually implying the need for renal replacement therapy.
Prerenal azotemia is caused by a decrease in blood flow (hypoperfusion) to the kidneys; however, there is no inherent disease of the kidney tissue. It can occur following hemorrhage, shock, volume depletion, congestive heart failure, adrenal insufficiency, and narrowing of the renal artery among other things.