What is acute kidney injury?

Acute kidney injury: Overview

Acute kidney injury (AKI) is a sudden decrease in kidney function. This can happen over a period of hours, days or, in some cases, weeks. AKI used to be called acute renal failure, but kidney failure doesn't always happen with AKI. Common causes of AKI are serious infection, blood loss, and some medicines.

When AKI happens, the kidneys have trouble removing waste and excess fluids from the body as urine. The waste and fluids build up and become harmful.

Kidney function may return to normal if the cause of AKI is treated quickly. Your chance of a full recovery depends on what caused the problem, how quickly the cause was treated, and what other medical problems you have. You may have a treatment called dialysis. It does the work of healthy kidneys to remove waste and fluids for a short time.

Acute kidney injury

Acute kidney injury, also called acute renal failure, is the sudden loss of kidney function. When acute kidney injury occurs, the kidneys are unable to remove waste products and excess fluids, which then build up in the body and upset the body's normal chemical balance.

The most common causes of acute kidney injury are serious infection, blood loss from major surgery or injury, or medicines such as nonsteroidal anti-inflammatory drugs (NSAIDs), antibiotics, or the dyes (contrast agents) used in X-ray tests.

Symptoms depend on the cause of the problem and can include:

  • Little or no urine output.
  • Dizziness upon standing.
  • Swelling, especially of the legs and feet.
  • Loss of appetite, nausea, and vomiting.
  • Feeling confused, anxious and restless, or sleepy.
  • Pain in the flank, which is felt just below the rib cage and above the waist on one or both sides of the back.

The treatment of acute kidney injury includes finding the cause and correcting it. Treatment also includes following a special diet, taking certain medicines, and possibly doing dialysis. This will continue until the kidneys are functioning normally. Most people who develop acute kidney injury are already in the hospital.

What happens when you have acute kidney injury?

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.

What are the symptoms of acute kidney injury?

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 vomiting.
  • Feeling confused, anxious and restless, or sleepy.
  • 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 treated?

Treatment depends on the cause of the kidney injury. For example, your doctor may restore blood flow to the kidneys, stop certain medicines, or fix a urinary blockage. You may have dialysis. It does the work of your kidneys until they recover. You may take medicines, like antibiotics, and follow a special diet.

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 problem.

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 can you care for an acute kidney injury?

  • Talk to your doctor about how much fluid you should drink.
  • Eat a balanced diet. Talk to your doctor or a dietitian about what type of diet may be best for you. You may need to limit sodium, potassium, and phosphorus.
  • If you need dialysis, follow the instructions and schedule for dialysis that your doctor gives you.
  • Do not smoke. Smoking can make your condition worse. If you need help quitting, talk to your doctor about stop-smoking programs and medicines. These can increase your chances of quitting for good.
  • Limit alcohol.
  • Review all of your medicines with your doctor. Do not take any medicines, including nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil, Motrin) or naproxen (Aleve), unless your doctor says it is safe for you to do so.
  • Make sure that anyone treating you for any health problem knows that you have had AKI.

What are the risk factors for getting acute kidney injury?

You have a greater chance of getting acute kidney injury if:

  • You are an older adult.
  • You have a long-term health problem such as kidney or liver disease, diabetes, high blood pressure, heart failure, or obesity.
  • 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 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 kidneys.
  • Damage from some poisons, infections, and medicines such as ibuprofen. People who have serious, long-term health problems, such as chronic kidney disease, are more likely to have a kidney problem from medicines. Injury can also be caused by many different diseases, including lupus and scleroderma.
  • 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.

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