Blood Urea Nitrogen (BUN)

Cleveland HeartLab B, Test

CPT Code: 84520
Order Code: C107
ABN Requirement:  No
Synonyms: Urea; BUN
Specimen: Serum
Volume: 0.5 mL
Minimum Volume: 0.2 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.

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


Ambient (15-25°C): 7 days
Refrigerated (2-8°C): 7 days
Frozen (-20°C): 1 year
Deep Frozen (-70°C): 1 year

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

Methodology: Photometric

Turn Around Time: 1 to 3 days

Reference Range:

Age mg/dL
0-18 years 5-18
≥19 years 8-23

Critical Value:

Age Critical Value mg/dL
All Ages ≥100

Intended Use: Blood urea nitrogen testing has utility in individuals at risk of kidney disease, such as those with hypertension or diabetes. It can also be used to monitor individuals with acute or chronic kidney disorders and to monitor kidney function.

Limitations: Ammonium ions may cause erroneously elevated results. In very rare cases gammopathy may cause unreliable results.

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.