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Test Code Billings Clinic: 4389 Urea Nitrogen (BUN), Dialysis, Plasma or Serum

Important Note

This test is for BIllings Clinic Dialysis patients Only.

 

Blood samples from some patients with monoclonal gammopathies may produce falsely elevated results.

Performing Laboratory

Billings Clinic Laboratory: Chemistry

Useful For

  • The determination of serum blood urea nitrogen currently is the most widely used screening test for the evaluation of kidney function.
  • The test is frequently requested along with the serum creatinine test since simultaneous determination of these 2 compounds appears to aid in the differential diagnosis of prerenal, renal and postrenal hyperuremia.

Methodology

Urease with GLHD / Bichromatic Rate

Specimen Requirements

Submit only 1 of the following specimens:

Serum or plasma should be physically separated from cells as soon as possible with a maximum limit of two hours from the time of collection.

 

Plasma

  • Draw blood in a green-top (lithium heparin) tube(s).
  • Spin down and send 0.5 mL of heparinized plasma frozen.

 

Serum

  • Draw blood in a plain, red-top tube(s) or a serum gel tube(s).
  • Spin down and send 0.5 mL of serum frozen

Storage/Stability

Specimen Type Temperature Time
Serum, Plasma Refrigerated 7 days
  Frozen (preferred) 1 month
  Ambient 5 days

Reject Due To

  • Gross hemolysis

Reference Values

7 - 18 mg/dL

Day(s) Test Set Up

Daily

Test Classification and CPT Coding

84520 - Urea nitrogen, quantitative

LOINC Code Information

Reporting Name LOINC Code
BUN 3094-0

 

Interferences

  • Hemoglobin at 250 mg/dL increases the UN result in serum/plasma at 9 mg/dL by 14%.
  • Conjugated bilirubin at 30 mg/dL decreases the UN result in serum/plasma at 40 mg/dL by -14%.