Acute kidney injury (AKI) is the sudden loss of kidney function. Kidneys clean waste from the blood and manage the balance of fluid in the body.

Anatomy of the Kidney

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There are many possible causes of sudden kidney failure because there are 3 anatomical sites for problems to occur in the renal system: before the blood enters the kidneys, within the kidneys, and after the urine is processed by the kidneys and enters the ureters.

AKI can result from problems with blood flow to the kidney, which can be caused by acute renal artery obstruction, blood loss, or dehydration. It can also result from conditions such as infections that interfere with the work of the kidney.

The most common cause of AKI occurs inside the kidney. Acute tubular necrosis is the death of the cells inside the kidney that act as the blood's filter. These cells die when they are deprived of oxygen. This can be due to surgical complications, inflammatory processes, blood clots, or the side effects of certain medications. Physical problems, such as swollen prostate glands or kidney stones can also cause AKI.

Risk Factors

Factors that may increase your chance of AKI include:

  • Having a chronic disease, such as diabetes, kidney disease, heart disease, liver disease, or high blood pressure
  • Increased age
  • Dehydration
  • Bleeding, especially from the gastrointestinal tract
  • Certain medications and illegal drugs
  • Complications following surgeries or care in an intensive care unit (ICU)
  • Overuse of certain nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Use of angiotensin converting enzyme (ACE) inhibitors
  • Obstructive causes such as benign prostatic hypertrophy and bladder tumor


Most people do not have symptoms. In those that have them, AKI may cause:

  • Less frequent urination
  • Swelling throughout the body
  • Dark-colored urine
  • Fatigue
  • Confusion
  • Nausea or vomiting
  • Muscle weakness or muscle cramps
  • No appetite
  • Metallic taste
  • In severe cases, coma or seizures


You will be referred to a kidney specialist (nephrologist) for diagnosis and treatment. You will be asked about your symptoms and medical history, including any medications you are taking. A physical exam will be done.

Your bodily fluids may be tested. This can be done with:

  • Blood tests
  • Urine tests

Imaging tests evaluate the kidney and surrounding structures. These may include:


Treatment for AKI will depend on the exact cause and severity. Your doctor may advise:

  • Dialysis—a machine used to filter waste from the blood
  • A catheter or stent to treat obstruction
  • IV fluids to maintain adequate blood volume
  • Stopping or changing medications that caused the loss of function
  • Treating related problems, such as kidney stones or infections
  • A supervised diet that limits protein intake
  • Kidney transplant


To help reduce your chance of AKI:

  • Get a physical every year that includes a urine test to monitor your kidney health.
  • Drink water and other fluids to stay hydrated.
  • Don't take drugs or other substances that can damage your kidneys. Ask about the side effects of any medications you are taking.
  • People at risk for chronic kidney disease should get more frequent check-ups at their doctor's office.