Sign in →

Test Code 0303 Urea Nitrogen, Urine, Timed

Performing Laboratory

Barnes-Jewish Hospital Laboratory


Enzymatic (Urease)

Literature Reference:

Package insert: Urea/BUN UREAL reagent. Roche Corporation, 03/2014.

Specimen Requirements

Specimen Type: Urine, timed

Container/Tube: Plain, brown urine container

Specimen Volume: Entire collection


Collection Instructions: No additive. Refrigerate specimen during collection.

Additional Information:

1. Starting and ending times of collection are required.

2. Follow instructions in Urine Collection in Special Instructions.

3. Brown urine container with green label (6N HCl) is acceptable.

Day(s) Test Set Up

Monday through Sunday
Turnaround Time:
STAT: 1 hour after receipt in laboratory
Routine: 2 to 4 hours after receipt in laboratory

Reference Values

No established reference intervals

Note: Calculation of nitrogen balance requires knowledge of 24-hour urea nitrogen and daily protein intake. Use the following formula: nitrogen balance=daily protein intake (g)/6.25-(24 hour urine urea nitrogen+3 or 4*).
*Use 4 if diarrhea is present.

Literature Reference:

Tietz, Burtis CA, Ashwood ER, Bruns DE eds: Textbook of Clinical Chemistry and Molecular Diagnostics 5th ed: Chapter 25, p. 669, Elsevier, St. Louis, MO 2012.

Test Classification and CPT Coding

81050-Volume measurement for timed collection

84540-Urea nitrogen

Additional Information

For BJH Laboratory Use Only

Analyte Stability:

See Analyte Stability Chart in Special Instructions.

Specimen must be kept refrigerated during collection and before delivery to limit bacterial growth.

Laboratory Processing Instructions:

Test performed in BJH Core Lab. Mix urine well. Record volume, period, and pH on request form. Using 13x100 test tubes, prepare a 7-mL aliquot and deliver to the automated line for centrifugation and delivery to Cobas 8000 for analysis. Completed specimen is stored refrigerated for 5 days.

Specimen Transport Temperature