Test Catalog

Test Id : URCON

Urea, Random, Urine

Useful For
Suggests clinical disorders or settings where the test may be helpful

Assessment of kidney failure (prerenal vs acute kidney injury)

Method Name
A short description of the method used to perform the test

Kinetic Ultraviolet Assay

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Urea, Random, U

Aliases
Lists additional common names for a test, as an aid in searching

BUN

Specimen Type
Describes the specimen type validated for testing

Urine

Ordering Guidance

A timed 24-hour urine collection is the preferred specimen for measuring and interpreting this urinary analyte. See URCR / Uric Acid, 24 Hour, Urine.

 

Random collections normalized to urinary creatinine may be of some clinical use in patients who cannot collect a 24-hour specimen, typically small children.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Supplies: Plastic, 5-mL tube (T465)

Container/Tube: Plastic tube

Specimen Volume: 4 mL

Collection Instructions:

1. Collect a random urine specimen.

2. No preservative.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

1 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 14 days
Frozen 30 days
Ambient 7 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

Assessment of kidney failure (prerenal vs acute kidney injury)

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Urea is a low molecular weight substance (60 Da) that is freely filtered by glomeruli, and the majority is excreted into the urine, although variable amounts are reabsorbed along the nephron. It is the major end-product of protein metabolism in humans and other mammals. Approximately 50% of urinary solute excretion and 90% to 95% of total nitrogen excretion is composed of urea under normal conditions. Factors that tend to increase urea excretion include increases in glomerular filtration rate, increased dietary protein intake, protein catabolic conditions, and water diuretic states. Factors that reduce urea excretion include low protein intake and conditions that result in low urine output (eg, dehydration). Urea excretion is a useful marker of protein metabolism.

 

In oliguric patients with a rising creatinine a fractional excretion of urea below 35% is consistent with a prerenal cause, while values above 35% are more consistent with acute kidney injury.(1) The fractional excretion of sodium is also used for this purpose but may be more affected by diuretics. Therefore, the fractional excretion of urea may be particularly useful for patients receiving diuretics.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

No established reference values

 

Random urine urea may be interpreted in conjunction with serum urea, using both values to calculate fractional excretion of urea.

 

The calculation for fractional excretion (FE) of urea is

FE(U)= ([U(urine)XCreat(serum)]/[U(serum)XCreat(urine)]) X 100

Interpretation
Provides information to assist in interpretation of the test results

Fractional excretion of urea under 35% is consistent with a prerenal cause.

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Carvounis CP, Nisar S, Guro-Razuman S: Significance of the fractional excretion of urea in the differential diagnosis of acute renal failure, Kidney Int. 2002 Dec;62(6):2223-2229

2. Lamb EJ, Jones GRD: Kidney function tests. In: Rifai N, Horvath AR, Wittwer CT, eds: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:498-500

3. Bankir L, Trinh-Trang-Tan MM: Urea and the kidney. In: Brenner B, ed: The kidney. 6th ed. WB Saunders Company; 2000

Method Description
Describes how the test is performed and provides a method-specific reference

Urea is hydrolyzed by urease to form ammonia and carbon dioxide. The ammonia formed then reacts with ketoglutarate and reduced nicotinamide adenine dinucleotide (NADH) in the presence of glutamate dehydrogenase to yield glutamate and NAD(+). The decrease in absorbance is due to consumption of NADH as measured kinetically at 340 nm.(Package insert: Roche Urea/BUN. Roche Diagnostics; V 8.0 02/2020)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Sunday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

Same day/1 day to 24 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

84540

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports