Acute kidney injury is the abrupt decline in kidney function leading to a rise in serum creatinine and or a reduction in urine output. It can develop over hours to days. The causes of acute kidney injury can be divided into:
Prerenal causes include inadequate blood flow to the kidneys. Glomerular function is maintained but there is a decrease in the amount of blood filtered, affecting the amount of waste found in the body. This may be caused by decreased blood flow from the heart, hypertensive medications, or an obstruction in the major blood vessels.
Intrarenal conditions cause direct damage to the kidneys. This may be caused by insufficient blood supply to the kidneys, a condition called ischemia and nephrotoxins, which are toxic substances that damage the nephron physically. The main cause is acute tubular necrosis a condition that results in cell death within the kidney tubules.
Postrenal causes occur if there is an obstruction from the kidneys to the bladder. This is known as urinary tract obstruction. Blockages may occur from ureters (the tube where urine forms from the kidneys), bladder or urethra (the tube where urine flows out of the body). Urine then backflows into the kidney and causes dysfunction, as this causes the wastes to flow back.