Patient education: Acute kidney injury (The Basics)

What is acute kidney injury? — This is when the kidneys suddenly stop working. Normally, the kidneys filter blood and remove waste and excess salt and water (figure 1). "Acute" means sudden.

Another term for acute kidney injury is "acute kidney failure."

What causes acute kidney injury? — 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. This could be from 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. This could be from prostate problems (in males) and cancer. The blockage of urine causes pressure on the kidney, which leads to damage.

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, they can include:

●Urinating less or not urinating at all

●Blood in the urine, or red or brown urine

●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

●Shortness of breath

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, tell your doctor or nurse 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, they will do blood and urine tests.

Some people 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, too.

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.

How is acute kidney injury treated? — Treatment depends on what's causing the acute kidney injury and how severe the injury is.

●If your acute kidney injury is caused by a medicine, you will stop taking that medicine. To help your kidneys heal, your doctor might also give you steroid medicines.

●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, the kidneys will heal and work normally again. But it can take weeks to months for them to heal completely.

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

●Medicines

●Changes in your diet – Your doctor will tell you if you need to change what you eat. People with acute kidney injury usually have to avoid or limit foods that contain a lot of sodium (salt), potassium, and phosphorus. A dietitian (food expert) can help you plan healthy meals with the right amounts of each nutrient.

You might also need to limit how much water and fluid you drink each day. It might help to suck on hard candies or ice chips if your mouth feels dry.

●Kidney replacement therapy (also called "dialysis") – This treatment takes over the job of your kidneys until they can heal. It involves either:

•Hemodialysis – This 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. People have hemodialysis at least 3 times a week.

•Peritoneal dialysis – This 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.

If you have swelling in your legs and ankles, you can also try raising your legs up while you are sitting or lying down. This can help reduce the swelling.

What follow-up care do I need? — You will get more lab tests as you recover from acute kidney injury. This will help your doctor monitor how well your kidneys are working.

More on this topic

Patient education: Blood in the urine (hematuria) in adults (The Basics)
Patient education: Swelling (The Basics)
Patient education: Hemodialysis (The Basics)
Patient education: Peritoneal dialysis (The Basics)
Patient education: Chronic kidney disease (The Basics)
Patient education: Rhabdomyolysis (The Basics)
Patient education: Glomerular disease (The Basics)
Patient education: Hyperkalemia (The Basics)
Patient education: Dialysis and diet (The Basics)
Patient education: Low-sodium diet (The Basics)
Patient education: Low-potassium diet (The Basics)
Patient education: 24-hour urine collection (The Basics)
Patient education: Urinalysis (The Basics)

Patient education: Peritoneal dialysis (Beyond the Basics)
Patient education: Hemodialysis (Beyond the Basics)
Patient education: Chronic kidney disease (Beyond the Basics)