Healthy kidneys are vital organs that filter wastes from the blood and maintain proper fluid balance. Kidney, or renal, failure refers to temporary or permanent damage to the kidneys that results in loss of normal kidney function. There are two types of renal failure: acute and chronic. Acute renal failure: has an abrupt onset and is potentially reversible. Chronic failure: progresses slowly over at least three months and can lead to permanent renal failure. The causes, symptoms, treatments, and outcomes of acute and chronic renal failure are different. Diagnostic Procedures In addition to a physical exam and complete medical history, diagnostic procedures for renal failure may include the following: Blood tests to determine blood cell counts, electrolyte levels, and kidney function Urine tests Renal ultrasound, also called sonography; a noninvasive test in which a transducer is passed over the kidney producing sound waves that bounce off the kidney, transmitting a picture of the organ on a video screen. The test is use to determine the size and shape of the kidney and to detect a mass, kidney stone, cyst, or other obstruction or abnormalities. Kidney biopsy, in which tissue samples are removed (with a needle or during surgery) from the body for examination under a microscope to determine if cancer or other abnormal cells are present Computed tomography scan (also called a CT or CAT scan), a diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce cross-sectional images, both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general X-rays. Treatment Specific treatment for renal failure may include hospitalization; intravenous fluids to replace depleted blood volume; diuretic therapy or medications to increase urine output; close monitoring of important electrolytes such as potassium, sodium, and calcium; medications to control blood pressure; and diet restrictions. Depending on the severity of kidney failure, some people may develop severe electrolyte disturbances and toxic levels of certain waste products that are normally eliminated by the kidneys. Fluid overload also may develop. In these cases, dialysis may be needed. Treatment of chronic renal failure depends on the degree of kidney function that remains. Treatment may include medications to help with growth, prevent bone density loss, and/or to treat anemia; diuretic therapy or medications to increase urine output; specific diet restrictions; dialysis; and, if necessary, kidney transplantation.