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Urea Nitrogen (BUN)
Test Code38468
CPT Codes
84520<br>Limited Access Code
Includes
For Urea Nitrogen (BUN), Postdialysis Serum, the recommended code is 3292, Urea Nitrogen (BUN), Serum
Preferred Specimen
1 mL serum collected in a serum separator tube (SST)
Minimum Volume
0.5 mL
Other Acceptable Specimens
1 mL plasma collected in a sodium heparin or lithium heparin (green-top) tube, or plasma separator tube (PST)
Instructions
Centrifuge serum specimens within 1 hour of collection, transfer serum to a sterile, plastic, screw-capped vial(s), and ship at room temperature
Transport Container
Sterile, plastic screw-cap vial
Transport Temperature
Room temperature
Specimen Stability
Room temperature: 7 days
Refrigerated: 5 days
Frozen: 28 days
Refrigerated: 5 days
Frozen: 28 days
Methodology
Spectrophotometric
Setup Schedule
Set up: Daily; Report available: Next day
Reference Range
| Age | Males (mg/dL) | Females (mg/dL) |
| < 1 month | 4-12 | 3-17 |
| 1-11 months | 2-13 | 4-14 |
| 1-3 years | 3-12 | 3-14 |
| 4-19 years | 7-20 | 7-20 |
| ≥ 20 years | 7-25 | 7-25 |
Clinical Significance
Urea is the principle waste product of protein catabolism. BUN is most commonly measured in the diagnosis and treatment of certain renal and metabolic diseases. Increased BUN concentration may result from increased production of urea, due to (1) diet or excessive destruction of cellular proteins as occurs in massive infection and fevers; (2) reduced renal perfusion resulting from dehydration or heart failure; (3) nearly all types of kidney disease, and (4) mechanical obstruction to urine excretion such as is caused by stones, tumors, infection, or stricture. Decreased urea levels are less frequent and occurs primarily in advanced liver disease and in overhydration.
