Acute Kidney Injury is the loss of kidney function over a short period of time (less than 48 hours). The decrease in function could be a result of reduction in blood flow to the kidney, an abnormality sustained within the kidney, or an obstruction within the urinary tract. Symptoms include fatigue, fluid retention, loss of appetite, nausea and vomiting. However, often times the patient does not experience symptoms, which can make it difficult to detect Acute Kidney Injury. For this reason, routine blood tests often include the blood test (creatinine) that tests for kidney injury.