What is creatinine clearance

For a hour urine test, you must collect all of your urine for 24 hours. Empty your bladder completely first thing in the morning without collecting it. Note the time. Then collect your urine every time you go to the bathroom over the next 24 hours.

Having a blood test with a needle has some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain.

Afterward, the site may be sore. The hour urine sample has to be exact. This means all urine must be collected and properly stored during the test period. Otherwise the test results may not be accurate. This is a common problem with the creatinine clearance test.

Many healthcare providers use a formula based on your blood creatinine levels alone to estimate the GFR. If you are pregnant or have recently done intense exercise, such as running a marathon, your creatinine clearance rate could be higher than normal. Certain medicines can cause creatinine clearance levels to be lower than normal. These include cimetidine, procainamide, certain antibiotics, and quinidine. Certain conditions, such as diabetes and congestive heart failure, may also affect the results.

You don't need to prepare for this test. Tell your healthcare provider about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.

Dehydration generally causes BUN levels to rise more than creatinine levels. This causes a high BUN-to-creatinine ratio. Kidney disease or blocked urine flow from your kidney causes both BUN and creatinine levels to rise. How To Prepare You may be asked to: Not do any strenuous exercise for 2 days 48 hours before having the tests. Not eat more than 8 ounces of meat, especially beef, or other protein for 24 hours before the blood creatinine test and during the creatinine clearance urine test.

Drink plenty of fluids if you are asked to collect your urine for 24 hours. But don't drink coffee or tea. These are diuretics that cause your body to pass more urine than normal. How It Is Done Blood tests A health professional uses a needle to take a blood sample, usually from the arm. Timed urine test You collect your urine for a period of time, such as over 4 or 24 hours.

When you first get up, you empty your bladder. But don't save this urine. Write down the time you began. For the set period of time, collect all your urine. Don't get toilet paper, pubic hair, stool feces , menstrual blood, or anything else in the urine sample. Keep the collected urine in the refrigerator for the collection time. Empty your bladder for the last time at or just before the end of the collection period.

Add this urine to the large container. Then write down the time. How long the test takes The urine test will take 24 hours. The blood test will take a few minutes. How It Feels Blood test When a blood sample is taken, you may feel nothing at all from the needle. Urine test This test usually doesn't cause any pain or discomfort. Risks Risks of a blood test There is very little chance of having a problem from this test. Urine test There are no known risks from having this test.

Results These tests give information about how well your kidneys are working. Normal Each lab has a different range for what's normal. Blood creatinine, creatinine clearance, and BUN-to-creatinine ratios can be measured. High values High creatinine blood levels can be caused by: Serious kidney damage or chronic kidney disease. Kidney damage can be caused by a life-threatening infection, shock , cancer, or low blood flow to the kidneys.

Muscle injury and conditions. These include crush injuries, burns, rhabdomyolysis , muscular dystrophy , polymyositis, and strenuous exercises. This is low blood pressure with many causes including severe bleeding and very severe infection. High creatinine clearance levels can be caused by carbon monoxide poisoning and pregnancy. High BUN-to-creatinine ratios occur with sudden acute kidney problems.

This may be caused by shock or severe dehydration. A very high BUN-to-creatinine ratio may be caused by bleeding in the digestive tract. There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight, but may include:. Landry DW, Bazari H. Approach to the patient with renal disease.

Goldman-Cecil Medicine. Philadelphia, PA: Elsevier; chap Oh MS, Briefel G. Evaluation of renal function, water, electrolytes, and acid-base balance. St Louis, MO: Elsevier; chap The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call for all medical emergencies.

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