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|Approval req'd?||Yes, if testing is requested between midnight and 8:00 AM.|
|Performed by||Parnassus Chemistry|
|In House Availability||Test available 7 days per week from 8:00 AM to midnight only.|
|Method||Enzymatic conductivity, kinetic (urease)|
|Collection Instructions||Refrigerate the collection container during the collection period.
Submit serum (Gold top) drawn within 24 hours of urine collection-preferably within the interval of collection.
Include the patient's weight in kg and height in cm on the requisition if a corrected clearance is needed.
|Container type||24 hour urine container AND Gold top vacutainer
Click here for Urine Preservative Requirements
|Amount to Collect||Entire 24 hour urine output
2 ml blood
|Sample type||24 hour urine AND serum|
|UCSF Rejection Criteria||Container not refrigerated during collection.|
|Normal range||See additional information|
|Stability||Refrigerated 2 days.|
|Turn around times||4 hours|
|Additional information||In normal individuals, urea clearance ranges between 35% - 65% of the GFR depending on hydration status (Diseases of the Kidney and Urinary Tract, R.W Schrier, 8th edition, 2007).
Note: Clearances are often inaccurate because of incomplete urine collection. A 4- or 6-hour collection is likely to be more complete than the classic 24 hour test, but extrapolation of results from shortened collections may not be accurate.
An order for Urea Clearance includes the following parameters:
a. Urine Urea Nitrogen: (Urine urea nitrogen mg/dL x Total Vol in mL x 24) / (100,000 x hours of collection) = g/d
Note: Only Urine Urea Nitrogen will be reported if no serum sample is received.
b. Urea Clearance Uncorrected: (Urine urea nitrogen mg/dL x Total Volume mL) / (60 x hours of collection x serum urea nitrogen) = mL/min
c. Corrected Urea Clearance: (Total Vol. in mL x urine urea nitrogen mg/dL x 1.73) / (60 x hours of collection x serum urea nitrogen x surface area) = mL/min/1.73 m2
|Last Updated||1/30/2013 12:22:44 PM|
|Lab Procedure Link||Click here for Procedure|
If you have additional questions regarding this test, please call: 415-353-1667