A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #

FUN / BUN

Message
Testing requires both Serum AND Filtrate sample to be submitted to the laboratory at the same time.


Test Code
FUBUN


Alias/See Also
Epic: LAB2285


Includes
Filtrate Urea Nitrogen (FUN)
Blood Urea Nitrogen (BUN)
FUN:BUN Ratio


Preferred Specimen

Both serum and plasma are required for this test.

Specimen Type: Serum
Collection Container: Serum gel
Specimen Volume: 3 mL

Specimen Type: Filtrate
Collection Container: Clear top (no additive)
Specimen Volume: 3 mL




Minimum Volume

0.25 mL of serum and 0.25 mL of filtrate




Instructions
Collection Instructions: 
  1. Collect venous blood in the serum gel tube.
  2. Filtrate specimen should be collected by the nurse at the same time and placed in a sterile tube.
  3. Clearly label the filtrate sample as "filtrate."
Additional Information:
  1. Both specimens should be sent to the lab together.
  2. If both specimens are not collected and sent together the tests will be cancelled.


Specimen Stability

Serum
Room temperature: 7 days
Refrigerated: 7 days
Frozen: 1 year

Filtrate
Room temperature: Unacceptable
Refrigerated: 5 days
Frozen: Unacceptable




Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Unlabeled, mislabeled, wrong tube type, QNS, exceeds specimen stability requirements.




Methodology

Urease



Setup Schedule

Daily




Report Available

Same day




Reference Range
See laboratory report


Clinical Significance
FUN/BUN ratio is used in checking and updating dialysate information by ICU for patients who are on CRRT (Continuous Renal Replacement Therapy).  The test is always run on BOTH serum and dialysate collected at the same time and is always Stat.


Performing Laboratory

Inova Laboratories

2832 Juniper Street

Fairfax, VA 22031




Last Updated: March 28, 2023
Last Review: N. Wolford, March 28, 2023


The CPT Codes provided in this document 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 payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.