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

What is acute kidney injury?

Acute kidney injury
(which used to be called acute renal failure) means that your
kidneys have suddenly stopped working normally. Your kidneys
remove waste products and help balance water and salt and other minerals (electrolytes) in your blood. When your kidneys stop
working, waste products, fluids, and electrolytes build up in your body. This
can cause problems that can be deadly.

What causes acute kidney injury?

Acute kidney injury has three main causes:

  • A sudden, serious drop in blood flow to the kidneys. Heavy blood loss, an injury, or a bad
    infection called
    sepsis can reduce blood flow to the kidneys. Not
    enough fluid in the body (dehydration) also can harm the
  • Damage from some medicines, poisons, or infections. Most people don’t have any kidney problems from taking
    medicines. But people who have serious, long-term health problems are more likely
    than other people to have a kidney problem from medicines. Examples of medicines that
    can sometimes harm the kidneys include:

    • Antibiotics, such as gentamicin and
    • Pain medicines, such as naproxen and
    • Some blood pressure medicines, such as ACE
    • The dyes used in some X-ray tests.
  • A sudden blockage that stops urine from flowing out of the kidneys. Kidney stones, a tumor, an
    injury, or an enlarged prostate gland can cause a blockage.

You have a greater chance of getting acute kidney injury

  • You are an older adult.
  • You have
    a long-term health problem such as kidney or liver disease,
    high blood pressure,
    heart failure, or
  • You are already very ill and are
    in the hospital or intensive care (ICU). Heart or belly surgery or a
    bone marrow transplant can make you more likely to
    have kidney problems.

What are the symptoms?

Symptoms of acute kidney injury may include:

  • Little or no urine when you
    try to urinate.
  • Swelling, especially in your legs and feet.
  • Not feeling like eating.
  • Nausea and
  • Feeling confused, anxious and restless, or
  • Pain in the back just below the rib cage. This is called
    flank pain.

Some people may not have any symptoms. And for people who are already quite ill, the problem that’s causing the kidney injury may be causing other symptoms.

How is acute kidney injury diagnosed?

Acute kidney injury is most often diagnosed during a hospital stay for another cause. If you are already in the hospital, tests done for other problems
may find your kidney problem.

If you’re not in the hospital but have symptoms of kidney injury, your doctor
will ask about your symptoms, what medicines you take, and what tests
you have had. Your symptoms can help point to the cause of your kidney

Blood and urine tests can check how well your kidneys are
working. A chemistry screen can show if you have normal levels of
sodium (salt),
potassium, and
calcium. You may also have an
ultrasound. This imaging test lets your doctor see
a picture of your kidneys.

How is it treated?

Your doctor or a kidney
specialist (nephrologist) will try to treat the problem that is causing your
kidney injury. Treatment can vary widely, depending on the cause. For example, your doctor may need to restore blood flow to the kidneys, stop any medicines that may be causing the problem, or remove or bypass a blockage in the urinary tract.

At the same time, the doctor will try to:

  • Stop wastes from building up in your body.
    You may have
    dialysis. This treatment uses a machine to do the work
    of your kidneys until they recover. It will help you feel
  • Prevent other problems. You may take antibiotics to prevent
    or treat infections. You also may take other medicines to get rid of extra
    fluid and keep your body’s minerals in balance.

You can help yourself heal by taking your medicines as
your doctor tells you to. You also may need to follow a special diet to keep
your kidneys from working too hard. You may need to limit sodium, potassium,
phosphorus. A dietitian can help you plan

Does acute kidney injury cause lasting problems?

Doctors sometimes can fix the problems that cause kidney
injury. The treatment takes a few days or weeks. These people’s kidneys will work well enough
for them to live normal lives.

But other people may have permanent
kidney damage that leads to
chronic kidney disease. A small number of them
will need to have regular
dialysis or a
kidney transplant. Older people and those who are
very sick from other health problems may not get better. People who die usually
do so because of the health problem that caused their kidneys to fail.

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Other Places To Get Help


National Kidney and Urologic Diseases Information Clearinghouse (U.S.)


Other Works Consulted

  • Kellum JA, et al. (2011). Acute kidney injury, search date December 2009. BMJ Clinical Evidence. Available online:
  • Kidney Disease: Improving Global Outcomes (KDIGO) Acute Kidney Injury Work Group (2012). KDIGO clinical practice guideline for acute kidney injury. Kidney International Supplements, 2(1): 1-138. Accessed January 9, 2015.
  • Lee BK, Vincenti FG (2013). Acute kidney injury and oliguria. In JW McAninch, TF Lue, eds., Smith and Tanagho’s General Urology, 18th ed., pp. 540-544. New York: McGraw-Hill.


ByHealthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD – Internal Medicine
Adam Husney, MD – Family Medicine
Kathleen Romito, MD – Family Medicine
Specialist Medical Reviewer Tushar J. Vachharajani, MD, FASN, FACP – Nephrology

Current as ofMay 3, 2017