What is the definition or description of: acute kidney failure?

Labs : An abrupt loss of renal function as determined (usually) by a rise in the serum creatinine. Definitions vary, a rise in creatinine of as little as 0.2mg/dl in a smaller person could be significant. There is no consistent description. It could be asymptomatic or the patient plagued with edema, lack of urine, sob, protein and or blood in the urine. Pain and dysuria could be present.