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This topic provides information about sudden kidney failure. If you are looking for information about long-term kidney disease, see the topic Chronic Kidney Disease.

What is acute renal failure?

Acute renal failure means that your kidneys have suddenly stopped working. Normally, the kidneys filter wastes and help balance water, salt, and mineral (electrolyte) levels in the blood. When your kidneys stop working, waste products, fluids, and electrolytes build up in your body. This can cause life-threatening problems.

What causes acute renal failure?

Acute renal failure has three main causes:

• A sudden serious drop in blood flow to the kidneys. The most common causes of low blood flow are severe blood loss, severe infection (sepsis), a serious injury, and dehydration. Most cases of acute renal failure result from reduced blood flow.
• Damage to the kidneys. Certain medicines, poisons, or infection can damage the kidneys. Problem medicines include antibiotics such as gentamicin and streptomycin, common pain medicines (nonsteroidal anti-inflammatory drugs) such as aspirin and ibuprofen, and the dyes used in some X-ray tests.
• A sudden blockage that prevents urine from flowing out of the kidneys. Kidney stones, a tumor, an injury, or an enlarged prostate gland can cause a blockage. This is a rare cause of acute renal failure.

You have a greater chance of developing acute renal failure if:

• You are an older adult.
• You have long-term (chronic) conditions such as kidney disease, liver disease, diabetes, high blood pressure, heart failure, or obesity.
• You are already seriously ill and are in the hospital or intensive care (ICU). Having heart surgery or stomach (abdominal) surgery or a bone marrow transplant can increase your risk.

What are the symptoms?

Acute renal failure often does not cause symptoms that you can notice. When symptoms do appear, they may include:

• Little or no urine output.
• Swelling, especially of the legs and feet.
• Loss of appetite, nausea, and vomiting.
• Feeling confused, anxious and restless, or sleepy.
• Pain on one side of the back, just below the rib cage and above the waist (flank pain).

If you are already in the hospital, tests done for other problems may also detect kidney failure.

How is acute renal failure diagnosed?

Your doctor will ask questions about your health to find out what medicines you have been taking, what tests you have had, and what symptoms you have noticed. The types of symptoms can help point to the cause of your kidney problem.

Your doctor will do blood and urine tests that check how well your kidneys are working. These include blood urea nitrogen (BUN), serum creatinine, complete blood count (CBC), and a urinalysis. A chemistry screen may be done to look for abnormal levels of electrolytes such as sodium, potassium, and calcium. You may also have an ultrasound, a test that lets your doctor see your kidneys.

How is it treated?

Your doctor or a kidney specialist (nephrologist) will try to find and treat the problem that is causing your kidneys to fail. At the same time, the doctor will focus on:

• Supporting your kidneys. Your doctor may order dialysis, which does the work of your kidneys until they recover. It will help you feel better and lets your kidneys rest while they heal.
• Preventing complications. You may take antibiotics to prevent or treat infections, and you may take other medicines to get rid of extra fluid and prevent electrolyte imbalances, which can be dangerous.

Treatment can usually reverse acute renal failure in a few days or weeks. But in some people it causes permanent kidney damage that leads to chronic kidney disease. About half of people who develop acute renal failure recover, and most of those who recover have kidneys that work well enough for them to live normal lives. Older adults and people who have other serious medical problems are less likely to regain their health.

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