Creatinine Blood Test

A creatinine blood test measures the level of creatinine in the blood. Creatinine is a waste product that forms when creatine, which is found in your muscle, breaks down. Creatinine levels in the blood can provide your doctor with information about how well your kidneys are working.

Normal levels of creatinine in the blood are approximately 0.6 to 1.2 milligrams (mg) per deciliter (dL) in adult males and 0.5 to 1.1 mg/dL in adult females. A person with only one kidney may have a normal level of about 1.8 or 1.9.

Acute renal failure occurs when the serum creatinine level increases by 0.5 mg/dL or more within 2 weeks or less. Signs and symptoms of acute kidney failure may include: Decreased urine output, although occasionally urine output remains normal. Fluid retention, causing swelling in your legs, ankles or feet. Shortness of breath.

Generally, a high serum creatinine level means that your kidneys aren't working well. Your creatinine level may temporarily increase if you're dehydrated, have a low blood volume, eat a large amount of meat or take certain medications. The dietary supplement creatine can have the same effect.

Low blood creatinine levels can mean lower muscle mass caused by a disease, such as muscular dystrophy, or by aging. Low levels can also mean some types of severe liver disease or a diet very low in protein. Pregnancy can also cause low blood creatinine levels.