Acute kidney failure occurs when your kidneys suddenly become unable to filter waste products from your blood. When your kidneys lose their filtering ability, dangerous levels of wastes may accumulate, and your blood's chemical makeup may get out of balance.

Acute kidney failure — also called acute renal failure or acute kidney injury — develops rapidly, usually in less than a few days. Acute kidney failure is most common in people who are already hospitalized, particularly in critically ill people who need intensive care.

Acute kidney failure can be fatal and requires intensive treatment. However, acute kidney failure may be reversible. If you're otherwise in good health, you may recover normal or nearly normal kidney function.

Symptoms

Signs and symptoms of acute kidney failure may include:

• Decreased urine output, although occasionally urine output remains normal
• Fluid retention, causing swelling in your legs, ankles or feet
• Shortness of breath
• Fatigue
• Confusion
• Nausea
• Weakness
• Irregular heartbeat
• Chest pain or pressure
• Seizures or coma in severe cases

Sometimes acute kidney failure causes no signs or symptoms and is detected through lab tests done for another reason.

Diagnosis

If your signs and symptoms suggest that you have acute kidney failure, your doctor may recommend certain tests and procedures to verify your diagnosis. These may include:

• Urine output measurements-: Measuring how much you urinate in 24 hours may help your doctor determine the cause of your kidney failure.
• Urine tests-: Analyzing a sample of your urine (urinalysis) may reveal abnormalities that suggest kidney failure.
• Blood tests-: A sample of your blood may reveal rapidly rising levels of urea and creatinine — two substances used to measure kidney function.
• Imaging tests-: Imaging tests such as ultrasound and computerized tomography may be used to help your doctor see your kidneys.
• Removing a sample of kidney tissue for testing-: In some situations, your doctor may recommend a kidney biopsy to remove a small sample of kidney tissue for lab testing. Your doctor inserts a needle through your skin and into your kidney to remove the sample.

Treatment

Treatment for acute kidney failure typically requires a hospital stay. Most people with acute kidney failure are already hospitalized. How long you'll stay in the hospital depends on the reason for your acute kidney failure and how quickly your kidneys recover.

In some cases, you may be able to recover at home.

Treating the underlying cause of your kidney injury

Treatment for acute kidney failure involves identifying the illness or injury that originally damaged your kidneys. Your treatment options depend on what's causing your kidney failure.

Treating complications until your kidneys recover

Your doctor will also work to prevent complications and allow your kidneys time to heal. Treatments that help prevent complications include:

• Treatments to balance the amount of fluids in your blood-: If your acute kidney failure is caused by a lack of fluids in your blood, your doctor may recommend intravenous (IV) fluids. In other cases, acute kidney failure may cause you to have too much fluid, leading to swelling in your arms and legs. In these cases, your doctor may recommend medications (diuretics) to cause your body to expel extra fluids.
• Medications to control blood potassium-: If your kidneys aren't properly filtering potassium from your blood, your doctor may prescribe calcium, glucose or sodium polystyrene sulfonate (Kionex) to prevent the accumulation of high levels of potassium in your blood. Too much potassium in the blood can cause dangerous irregular heartbeats (arrhythmias) and muscle weakness.
• Medications to restore blood calcium levels-: If the levels of calcium in your blood drop too low, your doctor may recommend an infusion of calcium.
• Dialysis to remove toxins from your blood-: If toxins build up in your blood, you may need temporary hemodialysis — often referred to simply as dialysis — to help remove toxins and excess fluids from your body while your kidneys heal. Dialysis may also help remove excess potassium from your body. During dialysis, a machine pumps blood out of your body through an artificial kidney (dialyzer) that filters out waste. The blood is then returned to your body.