ACUTE renal failure is a general term for the sudden development of impaired renal function from any of a number of causes (Table 1).Although oliguria (less than 300 or 400 ml. of urine per day) or anuria is usually present azotemia sometimes develops rapidly despite normal urinary output.DiagnosisAn important early step in management is to look for reversible or specifically treatable causes of acute renal failure, such as circulatory failure, obstruction, acute pyelonephritis, certain nephrotoxins and hypercalcemia. The urinary volume may be helpful in differential diagnosis. Complete anuria suggests obstruction or cortical necrosis; it occasionally occurs in . . .