Acute Renal Failure

Acute kidney injury

Acute kidney injury is when the kidneys suddenly stop working. Normally, the kidneys filter the blood and remove waste and excess salt and water. The word “acute” means sudden.

Another term for acute kidney injury is “acute kidney failure.”

Acute kidney injury can have different causes. It can happen when:

  • Less blood than usual flows to the kidneys. Different things can cause this to happen. For example, in a condition called heart failure, the heart might not be able to pump enough blood to the kidneys.
  • The kidneys get damaged. Some causes of kidney damage are infections, cancer, certain medicines, and some autoimmune conditions. In an autoimmune condition, a person’s infection-fighting system attacks their body.
  • The path the urine takes to leave the body is blocked. Some causes of blockages are prostate problems (in men) and cancer. The blockage of urine causes pressure on the kidney, which leads to damage.

Some people do not have any symptoms at first. People who are in the hospital might learn that they have acute kidney injury after they have blood tests for another reason.

When people do have symptoms, the symptoms can include:

  • Urinating less, or not urinating at all
  • Blood in the urine, or urine that is red or brown
  • Swelling, especially in the legs or feet
  • Vomiting, or not feeling hungry
  • Feeling weak, or getting tired easily
  • Acting confused, or not acting like themselves
  • Seizures – Seizures are waves of abnormal electrical activity in the brain. They can make people pass out, or move or behave strangely.

Call your doctor or nurse if you have any of the above symptoms. If you are already in the hospital, let your doctor or nurse know if you have any of these symptoms.

Yes. Your doctor will ask about your symptoms and do an exam. To check how well your kidneys are working, they will do blood and urine tests.

Most people will have an imaging test called an ultrasound to look for blockages in the urinary system. Imaging tests can create pictures of the inside of the body.

Your doctor might do other tests to look for other causes of your acute kidney injury. These can include X-rays or other imaging tests of your belly or kidneys.

If these tests don’t show what’s causing your acute kidney injury, your doctor might do a test called a biopsy. For a biopsy, the doctor will put a needle into your back and into your kidney. They will remove a tiny sample of tissue. Then another doctor will look at the sample under a microscope.

Treatment depends on what’s causing your acute kidney injury and how severe the kidney injury is.

If your acute kidney injury is caused by a medicine, your doctor will have you stop taking that medicine. Plus, to help your kidneys heal, they might also give you medicines called steroids. (These steroids are different from the ones athletes take to build muscle.)

If your acute kidney injury has another cause that can be treated, your doctor will treat it. For example, doctors can treat infections with antibiotics.

Most of the time, a person’s kidneys will heal and work normally again. But it can take weeks to months for the kidneys to heal completely.

Until your kidneys can work normally again, you might need treatments to help make sure your body has the right amount of fluid, salt, and nutrients. These treatments can include:

  • Medicines
  • Changes in your diet
  • Renal replacement therapy – This treatment takes over the job of your kidneys until they can heal. It involves either:
  • Hemodialysis – Hemodialysis is a procedure in which a machine takes over the job of the kidneys. The machine pumps blood out of the body, filters it, and returns it to the body (figure 2). People have hemodialysis at least three times a week.
  • Peritoneal dialysis – Peritoneal dialysis is a procedure that people do at home every day. It involves piping a special fluid into the belly. This fluid collects waste and excess salt and water from the blood. Then the used fluid drains out of the belly.