Acute kidney failure is a sudden loss of function that is sometimes but not always reversible. Chronic kidney failure is an irreversible loss of function that occurs gradually over months or years. Failing kidneys can't adequately clear the blood of certain toxins. As a result, when the kidneys fail, there is an abnormally high levels of these wastes products. Failing kidneys may also produce extremely dilute urine or urine that contains too much protein.
Healthy kidneys produce concentrated urine that is relatively protein-free.
To determine the prognosis of kidney disease, blood and urine tests are performed frequently during treatment to evaluate how well the kidneys are responding. A complete blood count looks at the numbers of red and white blood cells and a blood chemistry panel will examine the levels of waste products and electrolytes, indications of whether the kidneys are functioning properly. It's a good sign if test results swing back toward normal within the first 48 to 72 hours of therapy. This is significant because it often indicates a drop in erythropoetin, a hormone secreted by the kidneys that stimulates RBC production. Elevations of these levels result from kidney failure.