Urea Nitrogen, Serum or Plasma

Also known as: BUN

Clinical Use

Use

The Urea Nitrogen, Serum or Plasma test, commonly referred to as Blood Urea Nitrogen (BUN), is a screening test used to evaluate kidney function. Elevated levels of urea nitrogen in the blood can indicate impaired kidney function or kidney disease. It is a standard component of basic metabolic panels and is used to help diagnose and monitor conditions that affect kidney function, as well as to assess the effectiveness of dialysis treatment.

Special Instructions

Not provided.

Limitations

The Urea Nitrogen test may have limitations in specificity as elevated BUN levels can occur due to non-renal factors such as high protein diet, gastrointestinal bleeding, dehydration, and increased protein catabolism. Conditions that lower urea production, such as liver disease, may result in lower BUN levels despite normal renal function. Sodium fluoride in specimens can interfere with the test, making it necessary to avoid such additives. Hemolysis, lipemia, and icterus may also impact results and should be avoided where possible.

Test Details

New York Approved

Methodology

Automated Analyzer (Clinical Chemistry)

Biomarkers

Urea Nitrogen

Analyte

BUN

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

LOINC Codes

Order Codes

3094-0 - BUN SerPl-mCnc

Result Turnaround Time

1 day

Specimen

Plasma

Volume

1 mL

Minimum Volume

0.2 mL

Container

ARUP Standard Transport Tube

Collection Instructions

Collect in plasma separator tube. Allow to clot at room temperature, separate serum or plasma from cells as soon as possible, within 2 hours of collection.