Creatinine is a metabolic product of creatine. After metabolic reactions, creatine gets transformed into creatinine and acts as the fuel that brings energy necessary for contraction of the muscles. Creatinine is considered the waste product and as such kidneys are responsible for its excretion in urine.
There are no special preparations for creatinine clearance test, but the doctor might recommend fasting before the test for several hours. Test will use your urine and blood samples and determine the level of creatinine for 24 hours. Because of that, the sample you bring to the lab should be sample of your urine produced throughout last 24 hours.
Creatinine Clearance Test Results
Creatinine clearance test is made to determine the level of creatinine in the urine, comparing it to the creatinine level in the blood. If the test reveals increased level of creatinine it means that there is something wrong with the kidneys. Because of that, this creatinine clearance test is used to detect kidney and other problems in the human body. Doctors find this test very useful in patients suffering from kidney and cardiovascular diseases, since these medical problems might also affect the proper functioning of the kidneys. The test is also used to establish the rate of filtration of all other toxic substances through the kidneys.
Normal level of creatinine is around 0.6 and 1.2 mg/dL.
If your creatinine level is lower than 0.6 mg/dL it might indicate that you don’t eat enough protein, or perhaps that your muscles are not big and strong as they should be, because of the muscular dystrophy. Age and other medical conditions, including pregnancy can also affect and decrease the level of creatinine in the urine and blood. Sometimes, there is no reason to worry. If you drink plenty of water, it can also affect the level of creatinine and lower it significantly.
Creatinine level higher than 1.2 mg/dL is the sign of kidney problems. Elevated creatinine points to serious condition caused by kidney failure. In some cases, patients with high level of creatinine could suspect on kidneycancer.
Normal creatinine levels in the blood are about 100 to 140 ml/min for men and 90 to 130 ml/min for women. These numbers are then used to calculate estimated glomerular filtration rate (eGFR), which should be between 95 and 125 ml/min.
If the results of the test are lower than 65 ml/min it indicates the kidney problem, and the values under 20 ml/min point to kidney failure. Pregnant women might experience increase of eGFR.