Acute Kidney Injury (AKI)

People are usually born with two kidneys, which filter waste and excess liquid from the blood. The kidneys also produce hormones that help strengthen bones, control blood pressure, and direct the production of red blood cells.

Acute kidney injury (AKI) is the term for sudden failure of the kidneys over a period of hours or a few days, usually as a complication of a disease or condition. It is typically not caused by a physical blow to the kidneys, as the name might suggest.

AKI is distinguished from chronic kidney disease (the gradual loss of kidney function) by the speed of the kidney failure and also by the prospects for recovery. Patients with AKI may recover full kidney function. In chronic kidney disease, progressive damage is permanent and the goal of treatment is to prevent further decline in kidney function.

Acute kidney injury may be caused by:

• A sudden interruption or severe reduction in blood flow to the kidneys
• A disease or condition that directly damages the kidneys
• A blockage in the urinary tract

Reduced blood flow to the kidneys leading to AKI may be caused by:

• Low blood pressure, which can be the result of infection or shock
• Blood loss through internal or external bleeding
• Severe dehydration, which can be the result of diarrhea, for example
• Liver failure
• Use of NSAIDs (non-steroidal anti-inflammatory drugs), such as aspirin, ibuprofen, ketoprofen or naproxen
• Severe allergic reactions
• Serious burns
• Major surgery

Diseases and conditions that can directly damage the kidneys include:

• Hemolytic uremic syndrome (HUS)
• Glomerulonephritis
• Lupus
• Sepsis or severe infection
• Blood clots in the vessels to the kidneys
• Interstitial nephritis (an allergic reaction to certain types of medication)

Urinary tract blockage leading to AKI in children and adolescents can be caused by:

• Kidney stones
• Blood clots in the urinary tract
• Bladder problems

There may be no physical signs of acute kidney injury at first. Then symptoms can appear suddenly and grow more intense quickly.

Early signs of AKI may include:

• A decrease in the amount of urine produced
• Brown or red urine (a sign of blood in the urine)

As kidney function declines, other symptoms may include:

• Swelling of the hands or feet or in the face around the eyes
• Nausea and vomiting
• Extreme tiredness and lack of energy
• Shortness of breath
• Confusion
• Chest or stomach pain

AKI can progress quickly and can be life-threatening. Call your child’s doctor or seek emergency care immediately if you notice signs of kidney problems.

When physical symptoms and the patient’s history suggest acute kidney injury, additional tests are done to make a diagnosis. These may include:

• blood test to estimate the kidneys’ function (glomerular filtration rate or GRF)
• ultrasound, CT scan or MRI of the kidneys and urinary tract
• kidney biopsy

Once a diagnosis is made, further tests may be done to identify the cause of the kidney problem.

Treatment of acute kidney injury focuses on the causes of the kidney problems.

Depending on the cause of the AKI and the severity of the health problems, treatment may include:

• Antibiotics to eliminate infections
• Increased fluid intake
• IV fluids and nutrition
• Ending doses of medication found to be causing kidney problems
• Medication to control blood pressure

Close observation in the hospital may be needed until health is restored.

When AKI is not detected early or when treatment is unable to prevent serious damage to the kidneys, kidney failure may require treatment with:

• Dialysis
• Kidney transplantation

In most cases of acute kidney injury, treatment to address the causes can lead to full or significant recovery of kidney function.

In some cases, AKI progresses to chronic kidney disease. When that happens, the goal of treatment is to prevent further kidney damage.

When kidney function falls to levels that cause serious health problems, dialysis and kidney transplantation may be needed.

If the underlying problem is successfully addressed and full kidney function is restored, long-term follow-up care may not be necessary.

If the underlying problem requires ongoing treatment or if AKI causes permanent damage to one or both kidneys, follow-up appointments to manage health and monitor kidney function may be recommended.

The Division of Nephrology at Children's Hospital of Philadelphia (CHOP) provides your child with world-class care for and treatment of kidney diseases. Our division is consistently ranked as one of the top programs in the nation by U.S. News & World Report. Our physicians and staff are known for their ability to diagnose, treat and care for children with all forms of kidney disease, including acute kidney injury. Here, you'll find superb clinical care and an equal measure of understanding and compassion.

Our multidisciplinary team — including nephrologists, clinical nurse specialists, social workers, a pharmacist, psychologist, and nutritionist — provides comprehensive medical consultations and evaluations for children with renal diseases, electrolyte disorders and hypertension. The Division of Nephrology works closely with other providers, including the neonatal, pediatric, and cardiac intensive care units in the diagnosis and management of children with severe AKI.

Reviewed by: Benjamin Laskin, MD