A creatinine clearance test is used to help evaluate the rate and efficiency of kidney filtration. It is used to help detect kidney dysfunction and/or the presence of decreased blood flow to the kidneys. In patients with chronic kidney disease or congestive heart failure (which decreases the rate of blood flow), the creatinine clearance test may be ordered to help monitor the progress of the disease and evaluate its severity.

The creatinine clearance test may be ordered whenever a doctor wants to evaluate the filtration ability of the kidneys. It may be ordered when a patient has increased blood creatinine concentrations, a known or suspected kidney disorder, or decreased blood flow to the kidneys due to a condition such as congestive heart failure.

Any disease or condition that affects the glomeruli can decrease the kidneys’ ability to clear creatinine and other wastes out of the blood. When this occurs, the blood creatinine level will be increased and the creatinine clearance will be decreased because not as much creatinine is able to be excreted in the urine. A decreased creatinine clearance rate may also occur when there is decreased blood flow to the kidneys as may occur with congestive heart failure, obstruction within the kidney, or acute or chronic kidney failure. The less effective the kidney filtration, the greater the decrease in clearance.

Increased creatinine clearance rates may occasionally be seen during pregnancy, exercise, and with diets high in meat.

Patients with one dysfunctional and one normal kidney will usually have normal creatinine clearance rates as the functional kidney will increase its rate of filtration in compensation.

Creatinine clearance rates tend to fall later in life as the glomerular filtration rate (GFR – the rate at which the glomeruli filter the blood) declines.

Certain drugs, such as aminoglycosides, cimetidine, cisplatin, and cephalosporins, can decrease the creatinine clearance measurement. Diuretics can increase the result.