Urea Nitrogen Clearance

CPT: 84545
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Test Details


  • Urea Clearance
  • UUN Clearance

Test Includes

Blood urea nitrogen; urine clearance; urine urea nitrogen


Renal function test


Enzymatic (urease)

Specimen Requirements


Serum and urine (24-hour)


1 mL serum and 10 mL urine aliquot

Minimum Volume

0.5 mL serum and 1 mL urine aliquot


Gel-barrier tube or transport tube and plastic urine container


Serum must be drawn during urine collection. Separate serum from cells within 45 minutes of collection.

Storage Instructions

Maintain specimen at room temperature.

Stability Requirements



Room temperature

14 days


14 days


14 days

Freeze/thaw cycles

Stable x3

Clinical Information

Special Instructions

Must be a timed collection.


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
002329 Urea Nitrogen Clearance 001040 BUN mg/dL 3094-0
002329 Urea Nitrogen Clearance 135301 Urea Clearance mL/min 3098-1
002329 Urea Nitrogen Clearance 013508 Urea Nitrogen, U mg/dL 12967-6
002329 Urea Nitrogen Clearance 013236 Urea Nitrogen, 24hr g/24 hr 3096-5

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