Acute Kidney Injury

What Is It ?

Acute Kidney Injury (AKI) or Acute renal failure (ARF) is the temporary rapid breakdown of renal (kidney) function that occurs with high levels of uremic toxins (waste products of the body's metabolism) accumulate in the blood. AKI occurs when the kidneys are unable to excrete (discharge) the daily load of toxins in the urine.

Both kidneys are failing when Acute Kidney Injury (AKI) occurs. One normally functioning kidney can maintain adequate blood filtering.

AKI affects approximately 1% of patients on admission to the hospital, 2% to 5% during the hospital stay, and 4% to 15% after cardiopulmonary bypass surgery.

Based on the amount of urine that is excreted over a 24-hour period, patients with Acute Kidney Injury (AKI) are separated into two groups:

Oliguric: patients who excrete less than 500 milliliters per day (< 16 oz/day)

Nonoliguric: patients who excrete more than 500 milliliters per day (> 16 oz/day) In nonoliguric patients, the urine is of poor quality (i.e., contains little waste) because the blood is not well filtered, despite the fact that an adequate volume of urine is excreted.

Signs and Tests

Acute Kidney Injury (AKI) does not produce a classic set of symptoms. The most common symptom is decreased urine output, which occurs in 70% of patients.

AKI is most easily diagnosed by an increase in blood levels of creatinine and blood urea nitrogen (BUN). The blood level of creatinine typically increases by 0.5 milligrams per tenth of a liter (mg/dL) every day.


There are several modalities of renal replacement therapy (RRT) for patients with acute renal failure:
Intermittent Hemodialysis

  • Continuous Renal Replacement Therapy (Used In Critically ill Patients)
  • Slow Low Efficiency Dialysis (Used In Critically ill Patients)
  • Peritoneal Dialysis
Outlook (Prognosis)

Before the development of renal replacement therapy (RRT), many people with AKI died from severe electrolyte imbalance (hyperkalemia, acidosis) or from the uremic toxins themselves. Patients with ARF are at risk for numerous complications that may lead to death, such as seizures, bleeding, and coma.

Since dialysis effectively treats the life-threatening complications of AKI, advanced age and underlying diseases are more likely to determine the risk for a patient's dying from AKI.