BUN/Creatinine Ratio

Cleveland HeartLab B, Test


CPT Code: 82565, 84520
Order Code: 2968
ABN Requirement: No
Includes: Blood Urea Nitrogen (BUN), Serum Creatinine, BUN/Creatinine Ratio, Estimated Glomerular Filtration Rate (eGFR)
: Serum
Volume:  1.0 mL
Minimum Volume:  0.5 mL
Container: Gel-barrier tube (SST, Tiger Top)


  1. Collect and label sample according to standard protocols.
  2. Gently invert tube 5 times immediately after draw. DO NOT SHAKE.
  3. Allow blood to clot 30 minutes.
  4. Centrifuge for 10 minutes.

Fasting: Fasting is not required

Transport: Store serum at 2°C to 8°C after collection and ship the same day per packaging instructions included with the provided shipping box.


Ambient (15-25°C): 7 days
Refrigerated (2-8°C):
7 days
Frozen (-20°C):
3 months

Causes for Rejection: Specimens other than serum; improper labeling; samples not stored properly; samples older than stability limits

Methodology: Photometric Assay, Calculation

Turn Around Time:  1 to 3 days

Reference Range:

BUN, 0-18 Years5-18 mg/dL5-18 mg/dL
BUN, ≥19 Years8-23 mg/dL8-23 mg/dL
Creatinine, ≤2 Days0.79-1.58 mg/dL0.79-1.58 mg/dL
Creatinine, 3-27 Days0.35-1.23 mg/dL0.35-1.23 mg/dL
Creatinine, 1 Month- 9 Years0.20-0.73 mg/dL0.20-0.73 mg/dL
Creatinine, 10-12 Years 0.30-0.78 mg/dL0.30-0.78 mg/dL
Creatinine, 13-15 Years0.40-1.05 mg/dL0.40-1.00 mg/dL
Creatinine, 16-17 Years0.60-1.20 mg/dL0.50-1.00 mg/dL
Creatinine, 18-29 Years0.60-1.24 mg/dL0.50-0.96 mg/dL
Creatinine, 30-39 Years0.60-1.26 mg/dL0.50-0.97 mg/dL
Creatinine, 40-49 Years0.60-1.29 mg/dL0.50-0.99 mg/dL
Creatinine, 50-59 Years0.70-1.30 mg/dL0.50-1.03 mg/dL
Creatinine, 60-69 Years0.70-1.35 mg/dL0.50-1.05 mg/dL
Creatinine, 70-79 Years0.70-1.28 mg/dL0.60-1.00 mg/dL
Creatinine, ≥80 Years0.70-1.22 mg/dL0.60-0.95 mg/dL
BUN/Creatinine Ratio6-226-22


eGFR ≥60 mL/min/1.73m2

The eGFR is based on the CKD-EPI 2021 equation. To calculate the new eGFR from a previous Creatinine or Cystatin C result, go to https://www.kidney.org/professionals/kdogi/gfr%5Fcalculator.

Please Note: If results for BUN and Creatinine are both within the normal reference range, the BUN/Creatinine ratio will not be reported (not applicable).

Clinical Significance: The BUN/Creatinine ratio is useful in the differential diagnosis of acute or chronic renal disease. Reduced renal perfusion, e.g. congestive heart failure or recent onset of urinary tract obstruction, will result in an increase in BUN/Creatinine ratio. Increased urea formation also results in an increase in the ratio, e.g. gastrointestinal bleeding, trauma, etc. When there is decreased formation of urea, as seen in liver disease, there is a decrease in the BUN/Creatinine ratio. In most cases of chronic renal disease, the ratio remains relatively normal.

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.