Overview & Description
Creatinine is a waste product made by the body duringregular metabolism. It is excreted into the urine by the kidneys. Aserum creatinine test measures the level of creatinine in the blood.
The level of creatinine in the blood is a good measure ofoverall kidney function. When the kidneys are not working well forany reason, they are not able to excrete creatinine into the urine.When this happens, the level of creatinine in the blood rises.
Who is a candidate for the test?
Doctors may order this test when they think a person isdehydratedor has kidney damage. This test may also be ordered before or after adoctor prescribes certain medicines. The main reason to order thetest is to make sure the kidneys are working well.
How is the test performed?
To perform a serum creatinine test, a blood sample istaken from a vein on the forearm or hand. First, the skin over thevein is cleaned with an antiseptic. Next, a strong rubber tube called atourniquet is wrapped around the upper arm. This enlarges the veinsin the lower arm by restricting blood flow through them. A needle isgently inserted into a vein, and the tourniquet is removed. Blood flowsfrom the vein through the needle, and is collected in a syringe or vial.After the needle is withdrawn, the puncture site is covered with abandage for a short time to prevent bleeding. The blood sample issent to the laboratory to determine the amount of creatinine circulatingin the blood.
Preparation & Expectations
What is involved in preparation for the test?
Usually, no preparation is needed for this test. A personshould ask the doctor for specific instructions.
Results and Values
What do the test results mean?
The normal level of creatinine varies slightly based on age,body size, and sex. The level also changes duringpregnancy.However, the healthy range is usually between 0.5 and 1.4 milligrams perdeciliter (mg/dL).
A decreased value for this test is rarely a concern. It canoccur with decreased muscle mass, such as in elderly people.Conditions such as muscular dystrophy,which is an inherited defect in muscles, can cause a low value for this test.Pregnancymay also cause a low value.
A high value for this test can occur for many reasons. Some of thesereasons are described in the sections that follow.
Decreased blood flow to the kidneys
The blood flow to the kidneys can be decreased by the followingconditions or events.
Kidney damage or failure
The kidneys can be damaged by a number of conditions, including:
Other conditions can also cause an elevated value for this test:
The meaning of the results should be discussed with the doctor.
Article type: xmedgeneral