The level of creatinine in your body is a marker of kidney function. Creatinine comes from the breakdown of creatine, a muscle protein. Properly functioning kidneys remove creatinine from the blood.

Explanation of test results:

High levels of creatinine mean that the kidneys are not functioning properly. When creatinine levels rise gradually, there are not usually any symptoms, and the higher levels can be detected only with blood tests.

Other things to know:

• Certain medications can cause high levels of creatinine.
• A high creatinine level is sometimes referred to as "renal insufficiency" or "acute kidney injury."