This disorder is characterized by a sudden loss of the kidneys' ability to perform its functions, these include excreting wastes, concentrating urine and conserving electrolytes. The urine produced usually decreases in volume, and there may be no urine produced. This causes fluids and waste products to accumulate in the body. Lab tests show an accumulation of nitrogen wastes such as creatinine and urea in the body (azotemia). These waste products act as poisons when they accumulate in the body, damaging tissues and the functioning of many different organs. If the wastes are not removed from the body, death eventually results.

One of the functions of the kidney is to filter wastes and excrete fluid, this takes place when the pressure of blood in the bloodstream forces blood through the internal structures of the kidney. One cause of damage to the kidney could be decrease in blood flow. This may take place when there is extremely low blood pressure, occurring from trauma, complicated surgery, septic shock, hemorrhage, burns and associated dehydration, or other severe or complicated illness. Acute tubular necrosis (ATN) is another cause of acute renal failure; caused by ischemia (decreased oxygenation of the tissues) from obstruction or stricture of the renal artery. It may also occur following toxic injury to the kidney after exposure to metals, solvents, radiographic contrast, certain antibiotics and other medications, and other substances that are toxic to the kidney. Myoglobinuria (myoglobin in the urine) may cause acute renal failure; caused by rhabdomyolysis, alcohol abuse, crush injury, necrosis (tissue death) of muscles from any seizures and other causes. Acute renal failure may follow direct injury to the kidney. Also infections such as acute pyelonephritis orsepticemia may also be a cause. It may be a consequence of urinary tract obstruction such as a narrowing of the urinary tract (stricture), tumour, kidney stones, nephrocalcinosis, or enlarged prostate with subsequent acute bilateral obstructive uropathy. Severe acute nephritic syndrome can cause acute renal failure. Other causes include disorders of the blood, such as idiopathic thrombocytopenic purpura (ITP), transfusion reaction, or other hemolytic disorders. Causes also include malignant hypertension and disorders associated with childbirth such as postpartum renal failure and bleeding associated with placenta abruptio or placenta previa. Autoimmune disorders such as scleroderma may cause acute renal failure. Hemolytic uremic syndrome is one of the most frequent causes of acute renal failure in young children and appears to be increasing in prevalence. It is associated with the rapid onset of renal failure and other systemic manifestation. A toxin secreting bacterium, Eschereshia coli, found in contaminated undercooked meats, has been implicated as the cause of hemolyticuremic syndrome.

Treatment of causative disorders may help to prevent acute renal failure. Many cases may not be preventable.