Urea Nitrogen, Urine, Random Mnemonic U UN R Synonym Urea Nitrogen (UN) in Urine - Urine Urea Nitrogen (UUN) Specimen Collection Requirements Collect Urine, one sterile container without preservatives. Pediatric samples may be collected using a cotton ball. Handling Remove particulates by centrifugation prior to analysis. Preferred Volume 2.0 mL urine Minimum Volume 0.5 mL urine Transport Refrigerated (2-8°C) Stability Room Temperature (18-26°C): 48 hours; Refrigerated (2-8°C): 7 days; Frozen (at or below -20°C): 1 month Testing Information Performed 7 days/week Reported 24 hours Method Enzymatic Reference Values Reference Values Not Established CPT Codes 84540 Last Updated: Wednesday, February 3, 2021 01:13:38 AM Client Services: 503-413-1234