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Blood Urea Nitrogen (BUN)/Creatinine Ratio

Urea/Creatinine Ratio, BUN/Creatinine Ratio

Test Codes

EPIC: LAB1231108, Beaker: BCRR, Antrim: 13495

Department

Chemistry

Specimen Collection Criteria

Collect: One Gold-top SST tube. (Minimum Whole Blood: 4.0 mL)

Contact Laboratory for acceptability of other tube types. 
See Minimum Pediatric Specimen Requirements for Microtainer^® collection.

Physician Office/Draw Specimen Preparation

Let SST specimens clot 30–60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2–8°C or 36–46°F) the centrifuged SST tube within two hours of collection.

Preparation for Courier Transport

Transport: Centrifuged SST tube, refrigerated (2–8°C or 36–46°F). (Minimum: 0.5 mL)

Rejection Criteria

• Moderate to grossly hemolyzed specimens.
• Red-top tubes with serum not separated from cells within two hours of collection. 

In-Lab Processing

Let SST specimens clot 30-60 minutes. Centrifuge SST tubes or Microtainers^® to separate serum from cells. Deliver immediately to the appropriate testing station.

Storage

Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers^® with Separator Gel
Room Temperature (20–26°C or 68–78.8°F): 2-4 hours
Refrigerated (2–8°C or 36–46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers^® without Separator Gel
Room Temperature (20–25°C or 68–77°F): 2–4 hours
Refrigerated (2–8°C or 36–46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20–26°C or 68–78.8°F): 2-4 hours
Refrigerated (2–8°C or 36–46°F): 7 days
Frozen (-20°C/-4°F or below): 7 days

Specimen Storage in Department Prior to Disposal:

Refrigerated (2–8°C or 36–46°F): 7 days

Laboratory

Canton Laboratory
Dearborn Chemistry Laboratory
Farmington Hills Chemistry Laboratory 
Grosse Pointe Chemistry Laboratory 
Lenox Main Laboratory
Royal Oak Automated Chemistry Laboratory 
Troy Chemistry Laboratory
Taylor Chemistry Laboratory
Trenton Chemistry Laboratory
Wayne Chemistry Laboratory 

Performed

Sunday – Saturday, 24 hours a day.
STAT results available within 1 hour of receipt in the Laboratory.
Routine results available within 4 hours.

Reference Range

See specific tests for reference range.
This panel includes: BUN and Creatinine.

Test Methodology

Enzymatic Urease, Jaffe, Spectrophotometry.

Interpretation

See specific analytes for interpretation.
This panel includes: BUN and Creatinine.

Clinical Utility

Assessment of renal function. The ratio of BUN to creatinine may also be useful in the following instances:

• A ratio of 10–20 is normal. If BUN and creatinine are elevated, a normal ratio suggests intrinsic renal failure.
• A ratio of greater than 20 suggests prerenal failure or urinary tract obstruction.

CPT Codes

82565, 84520, 3097-3

Contacts

Last Updated

10/17/2024