The creatinine clearance test compares the level of creatinine in urine with
the creatinine level in the blood, usually based on measurements of a 24-hour
urine sample and a blood sample drawn at the end of the 24-hour period.
Clearance is often measured as milliliters/minute (ml/min).
Because
creatinine is found in stable plasma concentrations, is freely filtered and
not reabsorbed, and is minimally secreted by the kidneys, creatinine clearance
is used to estimate the glomerular filtration rate (GFR) -- the standard by
which kidney function is assessed.
A 24-hour urine sample generally required. Occasionally, 6- or 12-hour urine
collections can be done alternatively. The health care provider will instruct
you, if necessary, to discontinue drugs that may interfere with the test.
- On day 1, urinate into the toilet when you get up in the morning.
- Afterwards, collect all urine in a special container for the next 24
hours.
- On day 2, urinate into the container when you get up in the morning.
- Cap the container. Keep it in the refrigerator or a cool place during
the collection period. Label the container with your name, the date, the
time of completion, and return it as instructed.
A 24-hour urine sample generally required. Occasionally, 6- or 12-hour urine
collections can be done alternatively. The health care provider will instruct
you, if necessary, to discontinue drugs that may interfere with the test.
- On day 1, urinate into the toilet when you get up in the morning.
- Afterwards, collect all urine in a special container for the next 24
hours.
- On day 2, urinate into the container when you get up in the morning.
- Cap the container. Keep it in the refrigerator or a cool place during the
collection period. Label the container with your name, the date, the time of
completion, and return it as instructed.
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Common tests that are used to evaluate liver function include: