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Lab Manual for UCSF Clinical Laboratories

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UREA NITROGEN, SERUM, PLASMA

Item Value
Available Stat? Yes
Test code BUN
Performed by? Chemistry
Sendout? no
Price range $
In House Availability Routine: 7 days;
STAT: 24 hours/ 7 days
Principle The analysis is based on urease-catalyzed hydrolysis of urea to ammonia and carbon dioxide.
Interpretation Blood urea nitrogen (BUN) is related to the glomerular filtration rate.

1. Elevated BUN: usual causes are: acute or chronic renal disease due to glomerulonephritis, nephrosclerosis, or pyelonephritis; hemolytic anemia; hypotension due to hemorrhage; severe injury (burns, dehydration, heart failure); chemical injury or urinary tract obstruction.

2. Low BUN occurs in: chronic hepatic disease with liver failure, late pregnancy, low protein diet or malabsorption, and over hydration.
Container type gel tube (gold or green top)
Amount to Collect 2 mL
Sample type Blood
Normal range
Age mg/dL mcmol/L
0-1 yr 4-19 1.4-6.8
1-18 yrs 5-18 1.8-6.4


Age mg/dL mcmol/L
18-60 yrs 6-20 2.1-7.1
60-90 yrs 8-23 2.9-8.2
>90 yrs 10-31 3.6-11.1
Synonyms BUN;Metabolic Basic Panel (METB): NA, K, CL, CO2, CREA, BUN, GLUC, CA;
Stability Serum stable 1 day at room temperature; 2-3 days at 4°C, 6 months if frozen.
References 1. Tietz NW (ed). Fundamentals of Clinical Chemistry, 5th ed. Philadelphia: WB Saunders, pp 415-417, 2001.

2. Bayer(TM) Clinical Methods Urea Nitrogen (20) B01-4132-01 Advia 1650 Operator's Guide. PN 073-5001-09. Last accessed June 2003. Siemens Medical Solutions Diagnostics, Malvern, PA.
CPT coding 84520
Last Updated 11/12/2008 11:24:35 AM
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