Creatinine and Creatinine Clearance

Blood Creatinine

What To Think About

• A high blood creatinine level is generally seen with a low creatinine clearance level because creatinine in the blood is removed by the kidneys. If the kidneys are not able to remove creatinine (low creatinine clearance), levels of creatinine in the blood go up (high blood creatinine level).
• If you are pregnant, your doctor can check the amount of creatinine in amniotic fluid to see how developed, or mature, your baby's kidneys are. This can be helpful if there is a chance your baby will be delivered early. A baby who has mature kidneys will make more creatinine than a baby whose kidneys are still developing.
• A normal blood creatinine level does not rule out kidney disease. To help see whether kidney damage may be present, a BUN level is also measured. Other tests may also be done to check for kidney disease. For more information, see the medical test Blood Urea Nitrogen.
• Creatinine levels increase more slowly than blood urea nitrogen (BUN) levels, so an increase in creatinine may mean chronic kidney problems.
• A glomerular filtration rate may be done for people with chronic kidney disease to regularly check how well the kidneys are working.
• Diabetes experts recommend that blood creatinine levels be done every year for people with diabetes. The creatinine level is used to find the glomerular filtration rate, which shows how well the kidneys are working.
• The amount of creatinine in the blood depends partly on the amount of muscle tissue; blood creatinine levels are generally higher in men than in women. Also, people who have large muscles, such as athletes, normally have above-average blood creatinine levels.
• A one-time urine sample to measure urine creatinine and sodium is sometimes done along with blood creatinine and sodium levels to help find the fractional excretion of sodium (FENA). This test can help your doctor see whether a problem with blood flow to the kidneys is caused by dehydration or shock or by damage to the kidneys themselves.

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Author:	Jan Nissl, RN, BS	Last Updated: August 21, 2006
Medical Review:	Patrice Burgess, MD - Family Medicine
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