Written by the doctors and editors at UpToDate
What is 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 (figure 1). The word “acute” means sudden.
Another term for acute kidney injury is “acute kidney failure.”
What causes acute kidney injury? — 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 his or her body.
- The path the urine takes to leave the body is blocked. Some causes of blockages are prostate problems (in men) and cancer
What are the symptoms of acute kidney injury? — 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.
Should I call my doctor or nurse? — 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.
Is there a test for acute kidney injury? — Yes. Your doctor will ask about your symptoms and do an exam. To check how well your kidneys are working, he or she 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. He or she will remove a tiny sample of tissue. Then another doctor will look at the sample under a microscope.
How is acute kidney injury treated? — 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,he or she 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:
- 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 (figure3).
All topics are updated as new evidence becomes available and our peer review process is complete.
This topic retrieved from UpToDate on: Jan 08, 2019.
Topic 16930 Version 7.0
Release: 26.5.5 – C27.6
© 2019 UpToDate, Inc. and/or its affiliates. All rights reserved.
figure 1: Anatomy of the urinary tract
Urine is made by the kidneys. It passes from the kidneys into the bladder through two tubes called the ureters. Then it leaves the bladder through another tube called the urethra.
figure 2: Hemodialysis
This drawing shows a person getting hemodialysis. Two needles are put into an “access” in the person’s arm. Blood flows from the body to the hemodialysis machine, where it is filtered. Then the blood is returned to the body. The whole process takes about 3 to 5 hours and must be repeated 3 to 7 times a week.
Graphic 56992 Version 3.0
figure 3: Peritoneal dialysis
This drawing shows a person having peritoneal dialysis. The dialysis fluid (fresh dialysis solution) flows into the person’s belly. It stays there for a certain amount of time, and then it drains out into the drain bag. The “transfer set” is the tubing that connects a thin tube(catheter) in the person’s belly to the dialysis equipment.
Graphic 71539 Version 5.0