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BUN/Creatinine Ratio, Blood

Urea/Creatinine Ratio, BUN/Creatinine Ratio, Blood Urea Nitrogen/Creatinine Ratio, Blood, BCRR

Test Codes

EPIC: LAB1231108

Department

Chemistry

Specimen Collection Criteria

Collect:

FOR EC AND INPATIENT SAMPLE COLLECTION ONLY:
Preferred Sample:  One Light Green (Mint) Top Plasma Separator Tube (PST) (Minimum Whole Blood: 4.0 mL)
Acceptable Sample:  One Gold Top SST (Minimum Whole Blood: 4.0 mL)

FOR PHYSICIAN OFFICE/OUTREACH SAMPLE COLLECTION:
Collect:  One Gold Top SST (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 or PST 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): 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): 4 hours
Refrigerated (2–8°C or 36–46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum or Plasma Specimens (Pour-Overs)
Room Temperature (20–26°C or 68–78.8°F): 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): 5 days

Laboratory

Canton Laboratory
Dearborn Chemistry Laboratory
Farmington Hills Chemistry Laboratory 
Grosse Pointe Chemistry Laboratory 
Lenox Laboratory
Livonia 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 when received Monday – Friday. Results available within 24 hours on weekends and holidays.

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

3/6/2025