Patient education: Serum creatinine test (The Basics)

What is a serum creatinine test? — A serum creatinine test is a type of blood test that checks how well the kidneys are working. It measures the level of a substance called "creatinine" in the blood. Creatinine is a waste product created by muscles. "Serum" is the liquid part of the blood.

When the kidneys are working properly, they filter creatinine out of the blood. If the level of creatinine in the serum is too high, this can be a sign that the kidneys are not working properly.

Why might I get a serum creatinine test? — Your doctor might order a serum creatinine test:

●As part of a routine check-up

●If you have symptoms suggesting that you might have a kidney problem

●If you are at risk for developing kidney problems

●To check how well your kidneys are working, if you have already been diagnosed with a kidney problem

●To check how well a transplanted kidney is working

Based on the results of your serum creatinine test, your doctor or nurse will decide if you need other tests or treatment.

How do I prepare for a serum creatinine test? — For this test, you need to get a "blood draw." Your doctor or nurse will tell you where to go for this.

It might help to wear a short-sleeve shirt to your blood draw appointment. This makes it easier for the person drawing your blood to get to your arm.

What happens during a blood draw? — For the blood draw, a needle is used to take a small amount of blood from your arm (figure 1). Collecting the blood only takes a few minutes. The blood is then tested in a lab.

Tell the person who takes your blood:

●If you take "blood thinner" medicines or if you have a bleeding problem – They will make sure that your bleeding is under control before you leave.

●If you have a latex allergy – Some of the supplies used for blood draws might contain latex.

●If you have a preferred arm to use

Getting blood taken does not usually cause problems. You might have a little soreness or bruising where the needle went in.

What do my results mean? — Your doctor or nurse will tell you when to expect your results, and will contact you with the results. Or if you use an online "patient portal," you might get an alert there when your results are ready.

If your serum creatinine test shows any abnormal results, your doctor or nurse will talk to you about what to do next. They might need to do more tests to figure out what the cause is.

If you do have a health problem, your doctor will work with you to come up with a plan for treatment.

More on this topic

Patient education: Renal function panel (The Basics)
Patient education: Blood urea nitrogen test (The Basics)