Blood Urea Nitrogen (BUN)

Message

Performed in Chemistry

Test Code

BUN

CPT Codes
84520

Preferred Specimen

Green/Li
WyMCC - SST
Urine
Body Fluid

Other Acceptable Specimens

Green Top LiHep, Plasma

Specimen Stability

Serum:
Room Temperature 7 days
Refrigerated 7 days
Frozen 1 year

Urine:
Room Temperature 2 days
Refrigerated 7 days
Frozen 1 month

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Do not use ammonium heparin

FDA Status
FDA Approved

Setup Schedule

Daily, Sunday through Saturday

Report Available

Less than 4 hours

Clinical Significance

Urea is the major end product of protein nitrogen metabolism. It is synthesized by the urea cycle in the liver from ammonia which is produced by amino acid deamination. Urea is excreted mostly by the kidneys but minimal amounts are also excreted in sweat and degraded in the intestines by bacterial action. Determination of blood urea nitrogen is the most widely used screening test for renal function. When used in conjunction with serum creatinine determinations it can aid in the differential diagnosis of the three types of azotemia: prerenal, renal and postrenal. Elevations in blood urea nitrogen concentration are seen in inadequate renal perfusion, shock, diminished blood volume (prerenal causes), chronic nephritis, nephrosclerosis, tubular necrosis, glomerular nephritis (renal causes) and urinary tract obstruction (postrenal causes). Transient elevations may also be seen during periods of high protein intake. Unpredictable levels occur with liver diseases.

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.