Urea Nitrogen, 24-Hour Urine

TEST: 003541
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CPT: 84540
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Synonyms

  • BUN
  • Nitrogen Balance Study
  • Urine Urea Nitrogen

Special Instructions

Record total 24-hour urine volume on the request form.

Expected Turnaround Time

Within 1 day

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Related Information

Related Documents

Specimen Requirements

Specimen

Urine (24-hour)

Volume

10 mL aliquot of entire collection

Minimum Volume

1 mL aliquot (Note: This volume does not allow for repeat testing.)

Container

Plastic urine container, no preservative

Collection

Refrigerate the specimen as it is collected. Instruct the patient to void at 8 AM and discard the specimen. Then collect all urine including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning). Screw the lid on securely. Container must be labeled with patient's full name, date and time collection started, and date and time collection finished.

Storage Instructions

Room temperature

Stability Requirements

Temperature

Period

Room temperature

14 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Improper labeling

Test Details

Use

Renal function test; coarse nitrogen-wasting test on patients on hyperalimentation; indicate nitrogen balance in hyperalimentation; rule out tap of urinary bladder in amniocentesis, paracentesis

Methodology

Urease

Reference Interval

See table.

Age

Male (g/24 hr)

Female (g/24 hr)

0 to 5 y

Not established

Not established

6 to 17 y

3–21

2–13

18 to 70 y

5–22

4–16

>70 y

4–16

2–12

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
003541 Urea Nitrogen, 24-Hour Urine 013508 Urea Nitrogen, U mg/dL 3095-7
003541 Urea Nitrogen, 24-Hour Urine 013236 Urea Nitrogen, 24hr g/24 hr 3096-5

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