Why Are Both A Creatinine Clearance Test And A Serum Creatinine Test Done?

April 7, 2010

A creatinine clearance test is another name for a serum creatinine clearance test. This test is carried out to assess how well your kidneys are functioning and in particular how efficiently the kidneys pass out creatinine from your blood. Creatine is formed during metabolism; that is when the food is changed into energy. Creatine is then further broken down into creatinine which is passed out from your body in urine. Creatinine is not affected by physical exercise or diet. The creatinine levels in the urine go down and their level in the blood goes up, when the kidneys have been damaged. The creatinine clearance test is done on a blood sample as well as a 24 hour urine sample (urine which is collected over 24 hours).

The test is usually ordered as part of a routine check up or when you are very ill and show symptoms of kidney dysfunction which are:-

  • A decrease in the amount of urine
  • High blood pressure
  • Puffiness around the eyes, wrists, abdomen, ankles, thighs and face
  • Passing out foamy, coffee colored or bloody urine
  • Problems in urinating
  • Fatigue
  • A problem sleeping
  • Poor appetite
  • A lack of concentration
  • Pain below the ribs, where the kidneys are located.

High creatinine clearance levels could be a result of muscle injury, pregnancy, hypothyroidism, burns, strenuous exercise and carbon monoxide poisoning. Low creatinine clearance levels indicate that the kidneys are seriously damaged. This could be due to cancer, shock, urinary blockage, less blood flow to the kidneys or a life threatening infection. Liver cirrhosis, dehydration and heart failure could also result in low creatinine clearance levels.

Creatinine clearance levels generally decrease as you grow older. Men usually have higher levels than women as the creatine and creatinine levels depend on muscle mass. Be sure to tell your doctor if you are taking creatine as a dietary supplement as test results will show a higher level if this is the case.

It is important that you do not do any strenuous exercise for at least 48 hours before the test. Do not drink coffee or tea during the 24 hour urine collection but consume plenty of fluids. Coffee and tea are diuretics which will make you pass more urine. Refrain from eating more than 8 oz of meat (especially beef) or any other protein for 24 hours before the test.

Submitted by M T on April 7, 2010 at 02:48

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