Acute kidney injury (AKI)
Acute kidney failure is also called acute kidney injury or acute renal failure. It’s common in people who are already in the hospital. It may develop rapidly over a few hours. It can also develop over a few days to weeks. People who are critically ill and need intensive care have the highest risk of developing acute kidney failure.
Acute kidney injury (AKI) is sudden damage to the kidneys that causes them to not work properly. It can range from minor loss of kidney function to complete kidney failure.
AKI normally happens as a complication of another serious illness. It’s not the result of a physical blow to the kidneys, as the name might suggest.
This type of kidney damage is usually seen in older people who are unwell with other conditions and the kidneys are also affected.
It’s essential that AKI is detected early and treated promptly. The role of the kidneys is to:
- filter – removing waste and water from the blood (as urine, via the bladder)
- clean the blood
- keep the bones healthy
- look after blood pressure
- stimulate the bone marrow to make blood
Without quick treatment, abnormal levels of salts and chemicals can build up in the body, which affects the ability of other organs to work properly.
If the kidneys shut down completely, this may require temporary support from a dialysis machine, or lead to death.
Signs and symptoms
Signs and symptoms of acute kidney injury differ depending on the cause and may include:
- Too little urine leaving the body
- Swelling in legs, ankles, and around the eyes
- Fatigue or tiredness
- Shortness of breath
- Seizures or coma in severe cases
- Chest pain or pressure
- high blood pressure
- abdominal pain
- slight backache
In some cases, AKI causes no symptoms and is only found through other tests done by your healthcare provider.
Acute kidney injury can have many different causes. AKI can be caused by the following:
- Impaired blood flow to the kidneys
Some diseases and conditions can slow blood flow to your kidneys and cause AKI.
These diseases and conditions include:
- Blood or fluid loss
- Blood pressure medications
- Heart attack
- Heart disease
- Liver failure
- Use of aspirin, ibuprofen (Advil, Motrin IB, others), naproxen (Aleve, others) or related drugs
- Severe allergic reaction (anaphylaxis)
- Severe burns
- Severe dehydration
- Direct damage to the Kidneys
Some disease and conditions can damage your kidneys and lead to AKI. Some examples include:
- A type of severe, life-threatening infection
- A rare condition that causes inflammation and scarring to your blood vessels, making them stiff, weak, and narrow
- An allergic reaction to certain types of drugs
- A group of diseases that affect the connective tissue that supports your internal organs
- Conditions that cause inflammation or damage to the kidney tubules, to the small blood vessels in the kidneys, or to the filtering units in the kidneys
- Blockage of the urinary tract
In some people, conditions or diseases can block the passage of urine out of the body and can lead to AKI.
Blockage can be caused by:
- Bladder, prostate, or cervical cancer
- Enlarged prostate
- Problems with the nervous system that affect the bladder and urination
- Kidney stones
- Blood clots in the urinary tract
Acute kidney failure can occur when:
- You have a condition that slows blood flow to your kidneys
- You experience direct damage to your kidneys
- Your kidneys’ urine drainage tubes (ureters) become blocked and wastes can’t leave your body through your urine
The chances of acquiring acute kidney failure are greater if you’re an older person or if you have any of the following long-term health problems:
- kidney disease
- liver disease
- diabetes, especially if it’s not well controlled
- high blood pressure
- heart failure
- morbid obesity
If you’re ill or being treated in a hospital’s intensive care unit, you’re at an extremely high risk for acute kidney failure. Being the recipient of heart surgery, abdominal surgery, or a bone marrow transplant can also increase your risk.
When should AKI be suspected?
A doctor may suspect AKI in people known to be at risk who suddenly fall ill or develop symptoms which suggest complications of AKI.
AKI may also be suspected in people who have been unwell for a while and have either:
- chronic kidney disease
- a urinary system disease
- new or worsening urinary symptoms
- symptoms or signs of a disease affecting the kidneys and other organs
If you have acute kidney failure, you may have generalized swelling. The swelling is due to fluid retention.
Using a stethoscope, your doctor may hear crackling in the lungs. These sounds can signal fluid retention.
Results of laboratory tests may also show abnormal values, which are new and different from baseline levels. Some of these tests include:
- blood urea nitrogen (BUN)
- serum potassium
- serum sodium
- estimated glomerular filtration rate (eGFR)
- creatinine clearance
- serum creatinine
An ultrasound is the preferred method for diagnosing acute kidney failure. However, abdominal X-ray, abdominal CT scan, and abdominal MRI can help your doctor determine if there’s a blockage in your urinary tract.
Certain blood tests may also reveal underlying causes of acute kidney failure.