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Test Name:
Urea Nitrogen, Urine, 24-Hour
- SBMF No:
23375 - Performance Lab Name:
Automated Lab - Test Mnemonic:
U UN24 - ABN:
Not required - CPT Code:
84540 - LOINC Code:
12967-6; 3096-5; 13362-9; 3167-4; 20624-3; 2162-6; 19150-2 - Test Includes:
Urea Nitrogen (UUN)
Creatinine - Also Known As:
UUN (Urine Urea Nitrogen) - Spec Type:
Urine, 24-hour - Spec Container:
Plastic container with tightly fitting lid (no preservative) - Pref Vol:
20.0 mL aliquot from well-mixed 24-hour collection
Note: Send urine aliquot with notation of entire 24-hour urine volume on aliquot label and on requisition - Min Vol:
10.0 mL aliquot from well-mixed 24-hour collection - Fasting:
No - Spec Collect:
To begin collection of timed specimen, have patient urinate, noting date and exact time
Discard this first portion of urine, but document date and time of voiding on container label and test requisition as "start" of timed specimen
Save all urine voided during designated time period, including portion voided at exact end of time period
IMPORTANT: Refrigerate entire specimen (2-8°C) during and after collection to prevent bacterial growth
Document date and time of final voiding on label and requisition as "end" of timed specimen - Spec Process:
Upon completion of collection, mix entire specimen well and measure 24-hour volume
Pour off 20.0 mL of urine into separate plastic tube(s)
Refrigerate urine aliquot and transport refrigerated
Send urine aliquot with notation of entire 24-hour urine volume on aliquot label and on requisition - Spec Store Transport:
Refrigerated - Spec Stability:
48 hours refrigerated (2-8°C) - Spec Remarks:
Note: 24-hour urine is optimal specimen for testing - Methodology:
Enzymatic - Use:
Used in the diagnosis of certain renal and metabolic diseases - Clinical Significance:
The determination of urea is the most widely used test for the evaluation of kidney function. The test is frequently used in conjunction with the determination of creatinine for the differential diagnosis of prerenal hyperuremia (cardiac decompensation, water depletion, increased protein catabolism), renal hyperuremia (glomerulonephritis, chronic nephritis, polycistic kidney, nephrosclerosis, tubular necrosis) and postrenal hyperuremia (obstructions of the urinary tract).Urea is the final degradation product of protein and amino acid metabolism. In protein catabolism the proteins are broken down into amino acids and deaminated. The ammonia formed in this process is synthesized to urea in the liver. This is the most important catabolic pathway for eliminating excess nitrogen in the human body. - Reference Range:
12.0-20.0 g/24 hours - Additional Test Info:
Record total specimen volume, collection times, and pH [if required] on test requisition - Day Run:
Sun-Sat (daily) - Time Run:
As received - Time Reported:
4 hours - Test Type:
URINE
