BUN/Creatinine, Post Dialysis

Dialysis BUN/Creatinine, Blood Urea Nitrogen/Creatinine, PBCR2

Test Codes

EPIC: LAB1231109

Department

Chemistry

Instructions

This test is only available to Dialysis patients.

Specimen Collection Criteria

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 tube. (Minimum Whole Blood: 4.0 mL)
Contact the Laboratory for the acceptability of other tube types. 

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. (Minimum: 0.5 mL)

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 or PST specimens clot 30-60 minutes. Centrifuge SST or PST tubes and 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 (20-26°C or 68-78.8°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

Dearborn Chemistry Laboratory
Farmington Hills Chemistry Laboratory 
Grosse Pointe Chemistry Laboratory
Royal Oak Automated Chemistry Laboratory
Troy Chemistry Laboratory

Performed

Sunday – Saturday, 24 hours a day.
Results available within 4 hours.

Reference Range

Urea (BUN):

Age	mg/dL
0 – 15 days	3 - 23
15 days – 1 year	3 - 17
1 – 11 years	9 - 22
11 – 19 years	7 - 21
19 – adult	7 - 26

Creatinine (Male):

Male - Age	mg/dL	mg/dL
0 – 14 days	0.43	0.92
15 days – <2 years	0.10	0.36
2 – <5 years	0.20	0.43
5 – <12 years	0.31	0.61
12 – <15 years	0.45	0.81
15 – <19 years	0.62	1.8
19 – adult	0.60	1.30

Creatinine (Female):

Female - Age	mg/dL	mg/dL
0 – 14 days	0.32	0.92
15 days – <2 years	0.10	0.36
2 – <5 years	0.20	0.43
5 – <12 years	0.31	0.61
12 – <15 years	0.45	0.81
15 – <19 years	0.49	0.84
19 – adult	0.50	1.10

Test Methodology

Enzymatic Urease, Spectrophotometry, or Conductivity Electrode.

Interpretation

BUN results will be used for two calculations:

1. Kt/V (A dialysis dose calculation using patient's post dialysis weight, volume of ultrafiltrate (L), and BUN results.)
2. %URR (Urea Reduction Ratio) = 100*((pre-BUN - post-BUN)/pre-BUN)

Clinical Utility

This test is used to assess the adequacy of dialysis.

CPT Codes

84520, 82565.

Contacts

Last Updated

7/29/2026