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HelpTest Code UEBF Urea Nitrogen, Body Fluid
Reporting Name
Urea Nitrogen, BFUseful For
Identifying the presence of urine as a cause for accumulation of fluid in a body compartment
Assessing adequacy of peritoneal dialysis treatment protocols
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Body FluidNecessary Information
1. Date and time of collection are required.
2. Specimen source is required.
Specimen Required
Preferred Source:
-Peritoneal fluid (peritoneal, abdominal, ascites, paracentesis)
-Pleural fluid (pleural, chest, thoracentesis)
-Drain fluid (drainage, Jackson Pratt [JP] drain)
-Peritoneal dialysate (dialysis fluid)
-Pericardial
Acceptable Source: Write in source name with source location (if appropriate)
Collection Container/Tube: Sterile container
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Centrifuge to remove any cellular material and transfer into a plastic vial.
2. Indicate the specimen source and source location on label.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Body Fluid | Refrigerated (preferred) | 7 days | |
| Frozen | 30 days | ||
| Ambient | 24 hours |
Day(s) Performed
Monday through Sunday
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
84520
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| UEBF | Urea Nitrogen, BF | 3093-2 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| UE_BF | Urea Nitrogen, BF | 3093-2 |
| FLD15 | Fluid Type, Urea Nitrogen | 14725-6 |
Interpretation
Peritoneal and drain fluid concentrations should be compared to serum or plasma. A fluid to serum ratio of greater than 1.0 suggests the specimen may be contaminated with urine.(1)
Peritoneal dialysate urea nitrogen concentrations can be used to calculate the adequacy of peritoneal dialysis by monitoring solute clearance over time.(3)
All other fluids: Results should be interpreted in conjunction with serum urea nitrogen and other clinical findings.
Cautions
In very rare cases, gammopathy, in particular type IgM (Waldenstrom macroglobulinemia), may cause unreliable results.
Ammonium ions may cause erroneously elevated results.
Method Description
This is a kinetic ultraviolet assay where urease cleaves urea to form ammonia and carbon dioxide. The ammonia formed then reacts with alpha-ketoglutarate and nicotinamide adenine dinucleotide (NADH) in the presence of urease/glutamate dehydrogenase (GLDH) to yield glutamate and NAD. The decrease in absorbance, due to the consumption of NADH, is measured kinetically and is proportional to the amount of urea in the sample.(Package insert: Urea/BUN reagent. Roche Diagnostic Corp; V8.0 02/2020)
Report Available
Same day/1 to 2 daysSpecimen Retention Time
1 weekReject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
| Cerebrospinal fluid Breast milk Saliva Nasal secretions Gastric secretions Bronchoalveolar lavage (BAL) or bronchial washings Colostomy/ostomy Feces Urine Sputum Vitreous fluid |
Reject |
Method Name
Photometric
Clinical Information
Byproducts of nitrogen metabolism are present in high concentration in urine compared to blood and serve as a surrogate marker for the identification of urine leakage into a body compartment. Concentrations of creatinine or urea nitrogen that exceed the concentration found in a concurrent sample of blood are suggestive of the presence of urine.(1)
Peritoneal, abdominal, pelvic drain fluids:
Disruption of the urinary tract with subsequent leakage of urine into body cavities may be considered as part of the differential diagnosis when body fluid effusions develop of unknown origin.(2) Metabolites such as creatinine or urea that are contained in urine at high concentrations are good candidates to measure in body fluids for this investigation. Elevated concentrations may elicit a more focused radiologic examination to identify possible bladder rupture or perforation or the development of urinary fistula, which are typically corrected by surgical intervention.
Peritoneal dialysis fluid:
Peritoneal dialysis (PD) is a type of dialysis in which hyperosmotic fluid is passed into the patient's peritoneal cavity for a prescribed dwell time, wherein the peritoneum is employed as the dialysis membrane. The dwell fluid containing waste molecules removed by dialysis is drained and replaced with fresh fluid and the process repeated. Measurements of urea, creatinine, glucose, or other electrolytes in serum, urine, and the peritoneal dialysate fluid, aid in the assessment of peritoneal membrane transport characteristics and serve as markers of dialysis adequacy. Adequacy of PD is important to monitor because patients who maintain a sufficient clearance over time have longer survival.(2) Peritoneal urea clearance volume of distribution or urea (Kt/V) is calculated to measure solute clearance from the daily peritoneal urea clearance (Kt), and the volume of distribution of urea (V). Adequacy and membrane transport characteristics are calculated by plugging in the appropriate laboratory parameters into software packages used by dialysis centers.
Forms
If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.
Reference Values
An interpretive report will be provided.