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 Copyright © Nucleus Medical Media, Inc.

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 your symptoms and health history. You may also have:

• A physical exam
• Blood and urine tests—to measure levels of toxins and protein
• Imaging tests:
  • Kidney ultrasound
  • CT scan
  • MRI scan
  • MRA scan

Treatment

Care depends on the cause of AKI and how serious it is. 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
• Dietary changes that may limit how much salt and protein you eat
• IV fluids
• Dialysis —a machine works for your kidneys by filtering your blood
• Caring for problems such as kidney stones or infections

Prevention

Most AKI can not be prevented.