[NCI-GLOSS Definition]: A condition in which the kidneys stop working and are not able to remove waste and extra water from the blood or keep body chemicals in balance. Acute or severe renal failure happens suddenly (for example, after an injury) and may be treated and cured. Chronic renal failure develops over many years, may be caused by conditions like high blood pressure or diabetes, and cannot be cured. Chronic renal failure may lead to total and long-lasting renal failure, called end-stage renal disease (ESRD). A person in ESRD needs dialysis (the process of cleaning the blood by passing it through a membrane or filter) or a kidney transplant.

[CSP Definition]: Inability of a kidney to excrete metabolites at normal plasma levels under conditions of normal loading or inability to retain electrolytes under conditions of normal intake.

[RADLEX Definition]: A severe irreversible decline in the ability of kidneys to remove wastes, concentrate urine, and maintain electrolyte balance; blood pressure; and calcium metabolism. Renal failure, either acute (kidney failure, acute) or chronic (kidney failure, chronic), requires hemodialysis. [MeSH]

[NCIt Definition]: An acute or chronic condition that is characterized by the inability of the kidneys to adequately filter the blood.

[NICHD Definition]: An acute or chronic condition that is characterized by the inability of the kidneys to adequately filter the blood.