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Creatinine and Creatinine Clearance

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Creatinine and creatinine clearance tests measure creatinine levels in your blood and urine to give information about how well your kidneys are working. The creatinine clearance value is found from the amounts of creatinine in the urine and blood and from the amount of urine you pass in 24 hours. This value is the amount of blood cleared of creatinine per minute, based on your body size.

Normal

The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

Blood creatinine and creatinine clearance1

Blood creatinine:

Men: 0.6–1.2 milligrams per deciliter (mg/dL) or 53–106 micromoles per liter (mcmol/L)

Women: 0.5–1.1 mg/dL or 44–97 mcmol/L

Teen: 0.5–1.0 mg/dL

Child: 0.3–0.7 mg/dL

Creatinine clearance:

Men (younger than age 40): 107–139 milliliters per minute (mL/min) or 1.8–2.3 milliliters per second (mL/sec)

Women (younger than age 40): 87–107 mL/min or 1.5–1.8 mL/sec

Creatinine clearance values normally go down as you get older (normal values go down by 6.5 mL/min for every 10 years past the age of 20).

 

BUN-to-creatinine ratio1

Adults:

6–25, with 15.5 being the best value

 

High values

  • High creatinine blood levels. High creatinine blood levels can mean serious kidney damage or chronic kidney disease is present. Kidney damage can be caused by a life-threatening infection, shock, cancer, or low blood flow to the kidneys. Other conditions that can cause high blood creatinine levels include heart failure, dehydration, excessive blood loss that causes shock, gout, strenuous exercise, muscle injury (especially crushing injuries), burns, or muscle conditions (such as rhabdomyolysis, gigantism, acromegaly, myasthenia gravis, muscular dystrophy, and polymyositis). Usually a high blood creatinine level means that the creatinine clearance value is lower than normal.
  • High creatinine clearance. High creatinine clearance values can be caused by carbon monoxide poisoning, hypothyroidism, and pregnancy.
  • High BUN-to-creatinine ratio. High BUN-to-creatinine ratios occur with sudden (acute) kidney failure, which may be caused by shock or severe dehydration. A very high BUN-to-creatinine ratio may be caused by bleeding in the digestive tract camera.gif or respiratory tract camera.gif.

Low values

  • Low blood creatinine levels. 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.
  • Low creatinine clearance. Low creatinine clearance levels can mean you have chronic kidney disease or serious kidney damage. Kidney damage can be from conditions such as a life-threatening infection, shock, cancer, low blood flow to the kidneys, or urinary tract blockage. Other conditions, such as heart failure, dehydration, and liver disease (cirrhosis), can also cause low creatinine clearance levels.
  • Low BUN-to-creatinine ratio. A low BUN-to-creatinine ratio may be linked with a diet low in protein, a severe muscle injury called rhabdomyolysis, pregnancy, cirrhosis, or syndrome of inappropriate antidiuretic hormone secretion (SIADH). SIADH sometimes occurs with lung disease, cancer, diseases of the central nervous system, and the use of certain medicines.

WebMD Medical Reference from Healthwise

Last Updated: August 09, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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