What is Acute Kidney Injury?

An acute kidney injury (AKI) occurs when one or both kidneys are suddenly unable to filter dangerous toxins and other waste fluids from the body. Often the first indication of renal failure is a sudden decrease in urinary output and abdominal pain. There are three types of AKI: prerenal, intrinsic, and postrenal. The acute kidney injury is classified by the origin of the kidney failure.

Prerenal acute kidney injury refers to damages that result from a decrease of blood flow to and from the kidneys. General causes of prerenal AKI are related to changes in the blood volume of the body, or low blood pressure from heart disease. The kidneys are unable to produce enough urine to detoxify the body without adequate fluid pressure. If there is a blood clot leading to the kidney, the blood flow can be interrupted on the way to the kidney. The kidneys may recover after dialysis to remove the wastes accumulating in the body.

Intrinsic acute kidney injury is caused by damage to the kidney’s structure. The kidney may be malformed or inflammation may have set in the kidneys causing the kidneys to function improperly. The treatment for intrinsic acute kidney injury is dialysis, which replaces the filtering duties of the kidneys. In case of complete renal failure, a transplant may be needed of one or both kidneys.

Postrenal acute kidney injury results from an obstruction of the urinary tract. The kidneys may still be able to function normally, but a buildup of fluid from the filtration process causes the renal system to become overwhelmed with pressure and eventually decreases the efficiency of the kidneys. Treatment begins by inserting a catheter to relieve the pressure from trapped urine. The abdomen is then scanned by computer tomography (CT) to determine where the blockage has occurred. Finally, the blockage is removed, restoring the function of the kidneys.

Treatment for acute kidney injury focuses on replacing the function of the kidneys. The physician will order intravenous fluids to increase the pressure within the kidneys and encourage a larger urine output. If blood tests show a buildup of toxins, dialysis can be ordered continuously or two to three times a week. Acute kidney injury caused by the overuse of some medications, like acetaminophen or ibuprofen, may be relieved after the medications are no longer being used. In most cases, the kidneys will recover after treatment and dialysis can be discontinued.