Serum Creatinine Concentration (Mass Concentration)

This test measures the amount of creatinine in your blood, which helps show how well your kidneys are filtering waste from your body. Your provider may order it to check kidney function, monitor known kidney disease, or see how certain medicines are affecting your kidneys over time.

Creatinine levels can indicate how well your kidneys are working. High levels may suggest kidney damage or disease, while low levels could indicate dehydration or other conditions. Your doctor may order this test to monitor kidney health, especially if you have risk factors like diabetes, high blood pressure, or a family history of kidney problems.

In most cases, you can eat and drink normally before this blood test, but your provider may ask you to avoid eating a lot of meat or taking certain supplements beforehand. Tell your care team about all medicines you take, and drink water unless you are told otherwise.

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a larger panel. Drink plenty of water the day before to help dilute creatinine levels if needed. Avoid heavy exercise or strenuous activity 24 hours prior.

A nurse or technician will draw a small sample of blood, usually from a vein in your arm. The process takes only a few minutes. You may feel a quick pinch or sting when the needle goes in, and a small bandage will be placed on the spot afterward.

A healthcare professional will draw blood from a vein in your arm. The process takes a few minutes and may cause a slight pinch. You’ll feel no discomfort afterward.

Your results usually come back within a day or two, and normal ranges can vary by lab, age, sex, and muscle mass. If your creatinine is high, your provider may order additional tests, adjust your medicines, or talk with you about protecting your kidneys. Low results are often harmless but may still need follow-up.

Results are typically reported in milligrams per deciliter (mg/dL). Your doctor will compare your result to your baseline and any risk factors you have. If levels are abnormal, follow-up tests or treatments may be recommended to address kidney function or underlying causes.