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Test Code LAB6510 Urea Nitrogen, Urine, 24 hour

Performing Laboratory

St. Louis Children's Hospital Laboratory - Chemistry

Specimen Requirements

Patient Preparation: None

Collection Container/Tube:

Preferred: Plain, brown-orange 24-hour urine collection container without preservatives

Specimen Collection Volume: Entire urine specimen collected over 24 hour period.

Submission Container/Tube: If specimen is coming from outside facility, mix well and measure total volume before making aliquot with a minimum of 1.0 mL of urine into a plastic, leak-proof, screw-capped tube for transport labeling with volume and duration times or send entire 24-hr urine jug.

Special Instructions: 

  1. Refrigerate specimen during collection
  2. Note collection start and stop dates and times on collection container
  3. Call lab at 314-454-4268 to obtain 24-hour collection jug if needed
  4. Follow instructions on "Urine Collection"

Sample Rejection

Mislabled or unlabeled specimens

Logistics

Test Availability: Monday-Sunday

Cut-off time: None, performed as received

Turnaround Time: Same Day; 2 hours from receipt in performing lab

Reference Values

Reference Interval: 

<18 years: No reference values established                                     
≥ 18 years: 5-20 g/24 hours

Critical Value: None established

 

Methodology

Kinetic test (Urease withGlutamate Dehyrogenase) measured photometrically

Limitations

  • NA

Additional Information

FOR SLCH CORE LABORATORY USE ONLY

Lab Processing Instructions: Mix well and measure total volume collected. Centrifuge an aliquot of the urine to clear any precipatates aliquoting cleared urine into a Roche-false bottom tube for testing.

Processed Volume: minimum 0.3 mL urine

Analyte Stability:

Specimen Type Temperature    Time
urine (without preservative)     Ambient 2 days  
  Refrigerated     3 days   
  Frozen  1 month          

 

NOTE: 

  • Total volume of specimen collected and collection duration period is required. Note this information on the aliquot container label and into LIS system.
  • if collection duration is <18 hours or >30 hours cancel the 24Hr orderable and reorder test using the Timed orderable

 

Test Classification and CPT Code

84540

LOINC

UUN 24Ur:    3096-5

Volume Ur:    19153-6

Duration:       13362-9

Last Reviewed

07/2025