A measure of blood creatinine and a 24-Hour urine creatinine are used to calculate creatinine clearance. This test is used to help evaluate the rate and efficiency of kidney filtration (glomerular filtration rate). It is used to detect kidney dysfunction and/or the presence of decreased blood flow to the kidneys. Creatinine clearance also helps in monitoring the progress of kidney disease or congestive heart failure, and evaluates its severity. A DECREASED creatinine clearance rate may occur when there is a decreased blood flow to the kidneys as with congestive heart failure, obstruction within the kidney, or acute or chronic kidney failure. Any disease or condition that affects the glomeruli decreases the kidney’s ability to clear creatinine out of the blood, resulting in increased blood creatinine level and decreased creatinine clearance because not as much creatinine is able to be excreted in the urine. INCREASED creatinine clearance rates are occasionally seen during pregnancy, exercise, and with diets high in meat.