This test measures the amount of creatinine in the blood to assess kidney function. Creatinine is produced from muscle breakdown and removed from the blood by the kidneys. The test is used to evaluate kidney function and monitor conditions that could impact the kidneys like diabetes, heart disease, infections. A blood sample is needed and risks are minimal but may include bruising or infection at the puncture site. Normal levels vary depending on age but are generally below 1.5 mg/dL for adults.