Definition

Acute kidney injury (AKI) is the sudden loss of kidney function. Kidneys clean waste products from the blood and maintain fluid levels in the body. Problems can happen:

• Before blood enters the kidneys
• Inside the kidneys (most common)
• When urine leaves the kidneys and moves toward the bladder

Anatomy of the Kidney

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Causes

AKI has many causes:

• Blood is blocked from going into the kidneys because of:
  • Problems with blood vessels
  • Blood loss
  • Excessive fluid loss— dehydration
  • Infection
• Problems inside the kidney cause loss of filter because of:
  • Problems after surgery
  • Inflammation
  • Blood clots
  • Medicine side effects
• Kidney stones
• Enlarged prostate

Risk Factors

AKI is most common in older adults. Your chances are also higher if you have:

• Diabetes
• High blood pressure
• Kidney, liver, or heart disease
• Dehydration
• Bleeding from the stomach or intestines
• Taken certain medicines
• Used illegal drugs
• Problems after surgery or a hospital stay
• Overused certain nonsteroidal anti-inflammatory drugs (NSAIDs)
• Some blood pressure or heart medicine when dehydration is also present
• Blockages, which can happen with benign prostatic hyperplasia or a bladder tumor

Symptoms

Most people do not have symptoms. In those that have them, AKI may cause:

• Lower or higher amounts of urine than normal
• Dark or red urine
• Fatigue
• Confusion
• Nausea or vomiting
• Muscle weakness
• Muscle cramps
• Lack of hunger
• Swelling
• Weight gain

Diagnosis

The doctor will ask about symptoms and past health. Blood and urine tests will be done to measure levels of toxins and proteins. It will show how well the kidneys are working. Images of the kidneys may be taken with:

• Kidney ultrasound
• CT scan
• MRI scan
• MRA scan

Treatment

Care depends on the cause of AKI and how serious it is. The goal is to manage the cause and support the kidneys until they can work again. The kidneys may be able to recover normal function once they have had a chance to rest. Care may involve:

• Stopping or changing medicines causing harm to your kidneys
• Controlling blood pressure and diabetes
• Avoiding medicine that could be harmful such as NSAIDs common in over-the-counter pain medicine
• Limiting salt and protein in diet
• IV fluids
• Dialysis—a machine works for your kidneys by filtering your blood
• Caring for problems such as kidney stones or infections

Some AKIs can cause permanent severe damage to kidneys. Long term dialysis or a kidney transplant may be needed.

Prevention

Most AKI can not be prevented.