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Acute Kidney Injury (AKI)

The kidneys remove waste products from your body, regulate your blood pressure, and maintain the correct balance of electrolytes and minerals. Acute kidney injury (AKI) — also called acute kidney failure or acute renal failure — happens when your kidneys suddenly stop working.

If left untreated, AKI can cause permanent kidney damage. The kidney experts at UPMC can diagnose the cause of AKI and provide advanced treatment that reduces the risk of long-term complications.

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What Is AKI?

Acute kidney injury (AKI) — also called acute kidney failure or acute renal failure — happens when your kidneys suddenly stop working. Unlike chronic kidney disease, which causes kidney damage over time, AKI happens quickly — usually within hours or days.

Acute Kidney Injury Diagram Illustration Renal System

What are the types of AKI? 

There are three types of AKI based on the cause of the injury:

  • Intrarenal AKI — Occurs due to damage to your kidney tissue, often caused by trauma, disease, or exposure to toxins. Intrinsic AKI makes up 25% to 40% of AKI cases.
  • Postrenal AKI — Occurs when there is a blockage in your urinary tract and makes up 5% to 10% of AKI cases.
  • Prerenal AKI — Occurs when blood flow to the kidneys is reduced. Prerenal AKI is the most common type of AKI, making up 60% to 70% of AKI cases.

What causes acute kidney trauma?

Many health problems can cause acute kidney trauma. The most common health problems that cause AKI include:

Low blood pressure

Health problems that can cause low blood pressure include:

  • Burns.
  • Drug side effects.
  • Heart attacks or heart failure.
  • Other organ failure.
  • Overuse of pain medications or other drugs.
  • Severe diarrhea or other GI problems.
  • Severe starvation or dehydration.

Direct damage to your kidneys

Certain autoimmune and inflammatory diseases, trauma, and exposures to chemical toxins or drugs can directly damage your kidneys.

Blockages in your urinary tract

Issues that can block the flow of urine out of your body include:

  • An enlarged prostate.
  • Bladder dysfunction.
  • Certain cancers.
  • Kidney stones.

What are AKI risk factors and complications?

AKI risk factors

Factors that may increase your risk for acute kidney injury include:

  • Any serious condition that causes a hospital stay.
  • Being over the age of 60.
  • Certain cancers.
  • Diabetes.
  • Kidney disease of any kind.

Complications of AKI

Complications linked to acute kidney injury include:

  • Accumulation of drugs in your body that your kidneys normally process and associated side effects.
  • Fluid buildup in your lungs.
  • Life-threatening electrolyte problems, such as high potassium levels.
  • Permanent kidney damage.

How can I prevent AKI? 

You can’t always prevent AKI. However, a healthy lifestyle may reduce your risk of health problems that cause AKI.

Maintain a healthy weight and manage any health conditions that can increase your risk for kidney problems.

To further reduce your risk of AKI, you can:

  • Control chronic conditions — See a doctor for regular care if you have diabetes or high blood pressure.
  • Eat healthy — Eat a healthy diet with lots of fruits and vegetables. Limiting salt from shakers and processed foods can also help reduce your blood pressure.
  • Exercise — Aim for at least 30 minutes of moderate-intensity physical activity most days of the week.
  • Get preventive care — Check your blood pressure and blood sugar (glucose) routinely.
  • Keep track of medications — Inform your doctor if you routinely take over-the-counter drugs or herbal supplements and avoid or limit the use of NSAID medications (e.g., ibuprofen, naproxen).
  • Manage stress — Take steps to manage stress and get at least seven to eight hours of sleep each night.
  • Reduce alcohol intake — Limit alcohol to one drink a day for women and two drinks per day for men.
  • Stop smoking — Quit smoking if you smoke cigarettes or marijuana.

How common is AKI?

AKI is most common among people who are in the hospital for another health condition that puts their kidneys under extra stress. It is also more common in people with diabetes and in people who have another type of kidney disease.

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What Are the Signs and Symptoms of AKI?

If you have a mild form of AKI, it may not cause noticeable symptoms. Your doctor may diagnose AKI after routine blood tests or when running tests for other health conditions.

More severe cases of AKI may cause symptoms including:

  • Breathlessness.
  • Chest pain or pressure.
  • Confusion.
  • Coma.
  • Fatigue.
  • Nausea.
  • Seizures.
  • Swelling in your ankles, feet, or legs.
  • Urinating less often than usual.
  • Weakness.

When should I see a doctor about my AKI symptoms?

Getting fast treatment for AKI is key to reducing the risk of permanent kidney damage. If you notice symptoms of AKI, you should schedule an appointment with your doctor right away. If symptoms are severe, go to your nearest hospital emergency department.

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How Do You Diagnose AKI?

Your doctor will perform a physical exam, talk to you about your health history and recent activities, and order blood and urine tests to diagnose AKI.

What to expect during your visit

During your visit, your doctor will:

  • Ask about any medications you’ve taken recently.
  • Ask about recent activities, such as travel, injuries, or recreational drug use.
  • Perform a physical exam.
  • Order blood or urine tests.
  • Review your health history.

Tests to diagnose AKI

Your doctor may order blood or urine tests to diagnose AKI. Blood tests include:

  • Blood urea nitrogen (BUN) — Shows how well your kidneys are filtering urea nitrogen, a waste product, from your blood.
  • Electrolyte and other tests — Checks for imbalances in electrolyte and mineral levels in your body, such as sodium, potassium, and bicarbonate.
  • Estimated glomerular filtration rate (eGFR) — Shows how efficiently your kidneys function based on your age, creatinine level, and sex.
  • Serum (blood) creatinine — Shows how well your kidneys are filtering creatinine, a waste product, from your blood.

Urine tests include:

  • Urinalysis — Looks for abnormalities in your urine.
  • Urine output — Tracks how much urine your body produces each day.

Other less common tests include:

  • CT scan — A test that creates images of the organs, bones, and tissues in your body.
  • Kidney biopsy — A procedure that involves taking small pieces of kidney tissue for examination under a microscope to check for signs of disease.
  • Ultrasound — Uses sound waves to create images of your organs to check for problems.

AKI prognosis

Your prognosis depends on many factors, including the cause of your AKI and your overall health. Your doctor will discuss your prognosis with you.

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How Do You Treat AKI?

AKI treatment aims to help your kidneys heal and restore normal kidney function.

Your AKI treatment plan will depend on the cause and severity of your condition. After making an AKI diagnosis and finding the cause of your condition, your doctor will discuss your treatment plan with you.

You may need to stay in the hospital during your treatment and receive frequent follow-up care after you are discharged.

Treatment may include:

Observation

Mild cases of AKI sometimes get better on their own. If your AKI is not severe, your doctor may monitor your condition for several days to see if it improves.

Medicine to treat AKI

Your doctor may give you medications to regulate your blood pressure, fluid levels, or electrolytes.

Dialysis for AKI

If you have a severe case of AKI that causes your kidneys to stop working completely, you may need dialysis. Dialysis removes waste from your blood using a special machine that does the job of your kidneys until they recover. You may need dialysis on a temporary or permanent basis, depending on how well your kidneys heal.

Diet for AKI

To reduce stress on your kidneys during and after your AKI treatment, you may need to work with a registered dietitian and follow a special eating plan.

Can AKI be cured?

In some cases, AKI can be cured by treating the cause of kidney injury. However, AKI can sometimes cause permanent kidney damage.

Is acute kidney injury reversible?

AKI may be reversible if the cause of the injury is treatable and there is no permanent kidney damage.

How effective is AKI treatment? 

The effectiveness of AKI treatment depends on the cause of your condition and whether it has resulted in permanent kidney damage. Your kidneys may heal fully over time, or permanent damage may require ongoing treatment.

How long does it take to recover from AKI?

Mild cases of AKI may get better in a few days with observation or minimal treatment. Severe cases of AKI may get better in weeks or months or may cause permanent kidney damage that requires ongoing treatment. Your doctor will monitor your condition and discuss your expected recovery time.

Why choose UPMC for AKI care?

When you choose UPMC for AKI care, you will receive:

  • Access to world-class nephrology expertise — Our world-renowned experts treat the full spectrum of kidney diseases using the latest diagnostic and treatment techniques.
  • Advanced diagnostic care — We’ll find the cause of your kidney injury and work with you to develop a comprehensive treatment plan.
  • A full range of treatment options — We offer supportive care, dialysis, and kidney transplant, depending on your individual care needs.

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By UPMC Editorial Staff. Last reviewed on 2025-04-24 by Alexandra Bursic, MD.