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Test Code URAU Urea, 24 Hour, Urine

Reporting Name

Urea, U

Useful For

Assessment of protein intake and/or nitrogen balance

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Urine


Specimen Required


Container/Tube: Plastic, 5-mL tube (T465)

Specimen Volume: 4 mL

Collection Instructions:

1. Add 10 g of boric acid as preservative at start of collection. (If boric acid is not available, refrigerate specimen during collection.)

2. Collect urine for 24 hours.

3. Mix well before taking aliquot.

Additional Information:

1. 24-Hour volume is required.

2. See Urine Preservatives in Special Instructions for multiple collections.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Refrigerated (preferred) 14 days
  Frozen  14 days

Reference Values

10-35 g/24 hours

Day(s) and Time(s) Performed

Monday through Sunday; Continuously  

Test Classification

This test has been cleared or approved by the U.S. 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

84540

LOINC Code Information

Test ID Test Order Name Order LOINC Value
URAU Urea, U In Process

 

Result ID Test Result Name Result LOINC Value
UREA Urea, U 48999-7
TM33 Collection Duration 13362-9
VL31 Urine Volume 3167-4
URECN Urea Concentration 63481-6

Clinical Information

Urea is a low molecular weight substance (Mol. Wt.=60) 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 which tend to increase urea excretion include increases in glomerular filtration rate, increased dietary protein intake, protein catabolic conditions, and water diuretic states. Factors which reduce urea excretion include low protein intake and conditions which result in low urine output (eg, dehydration).

Interpretation

Because multiple factors (glomerular filtration rate, dietary protein intake, protein catabolic rate, hydration state, etc.) can independently affect the urinary excretion of urea, all of these factors must be taken into account when interpreting the results.

Clinical Reference

Bankir L, Trinh-Trang-Tan MM: Urea and the kidney. In The Kidney. Sixth edition. Edited by BM Brenner. Philadelphia, WB Saunders Company, 2000

Analytic Time

Same day/1 day

Reject Due To

Hemolysis

NA

Lipemia

NA

Icterus

NA

Other

NA

 

Method Name

Kinetic UV Assay 

Urine Preservative Collection Options

Ambient:

No

Refrigerated:

Yes

Frozen:

Yes

6N HCl:

Yes

50% Acetic Acid:

Yes

Na2CO3:

Yes

Toluene:

Yes

6N HNO3:

Yes

Boric Acid:

Preferred

Thymol:

Yes