Test Catalog

Test Id : NITU

Nitrogen, Total, 24 Hour, Urine

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

Assessing nutritional status (protein malnutrition)

 

Assessment of protein nutrition and nitrogen balance in hospitalized patients

 

Evaluating protein catabolism

 

Determining nitrogen balance, when used in conjunction with 24-hour fecal nitrogen measurement

Special Instructions
Library of PDFs including pertinent information and forms related to the test

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

Dumas Combustion

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

Nitrogen, Total, U

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

Nitrogen Balance

Total Urinary Nitrogen

TUN

Specimen Type
Describes the specimen type validated for testing

Urine

Necessary Information

24-Hour volume is required.

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

Supplies: Urine Tubes, 10 mL (T068)

Container/Tube: Plastic, 10-mL urine tube

Specimen Volume: 10 mL

Collection Instructions:

1. Collect urine for 24 hours.

2. No preservative. Refrigerated is the preferred preservation method.

Specimen Stability Information: Frozen -3 years

Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens in Special Instructions for multiple collections.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Urine Preservative Collection Options

Note: The addition of preservative or application of temperature controls must occur within 4 hours of completion of the collection.

Ambient

OK

Refrigerate

Preferred

Frozen

OK

50% Acetic Acid

OK

Boric Acid

No

Diazolidinyl Urea

No

6M Hydrochloric Acid

OK

6M Nitric Acid

No

Sodium Carbonate

OK

Thymol

OK

Toluene

No

 

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

2 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) 7 days
Ambient 7 days
Frozen

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

Assessing nutritional status (protein malnutrition)

 

Assessment of protein nutrition and nitrogen balance in hospitalized patients

 

Evaluating protein catabolism

 

Determining nitrogen balance, when used in conjunction with 24-hour fecal nitrogen measurement

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

Nitrogen is a key component of proteins. Nitrogen balance is the difference between the amount of nitrogen ingested and the amount excreted in the urine and feces. A majority of nitrogen is excreted as urea in the urine; however, fecal nitrogen can account for 30% to 50% of total nitrogen excretion.

 

A patient who is in negative nitrogen balance is catabolizing muscle protein to meet the metabolic requirements of the protein catabolism and, therefore, urine and fecal nitrogen may be increased due to stress, physical trauma, surgery, infections, burns, and 11-oxysteroid or thyroxine use. Testosterone and growth hormone have anabolic effects on protein synthesis and may decrease urine and fecal nitrogen.

 

In the course of chronic progressive pancreatitis, as the pancreas is destroyed, serum amylase and lipase may revert to normal. However, excessive fecal nitrogen levels persist and are used as an indicator of pancreatic atrophy.

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.

<16 years: not established

> or =16 years: 4-20 g/24 hours

Interpretation
Provides information to assist in interpretation of the test results

Urinary nitrogen excretion levels within the normal range are indicative of adequate nutrition. Slightly abnormal excretion rates may be a result of moderate stress or complications such as infection or trauma. Significantly abnormal excretion rates may be associated with severe stress due to multiple traumas, head injury, sepsis, or extensive burns. The goal with therapy for a depleted person is a positive nitrogen balance of 4 to 6 g nitrogen/24 hours.

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

Measurement of both urine and fecal nitrogen is necessary for the accurate determination of nitrogen balance.

 

During nitrogen balance studies, nitrogen lost from exuding wounds, such as burns, and from copious sputum must be included in the patient's evaluation.

 

Urine samples with visible blood may exhibit a positive bias for nitrogen due to the contribution of nitrogens present within hemoglobin.

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

1. Morse MH, Haub MD, Evans WJ, Campbell WW: Protein requirement of elderly women: nitrogen balance responses to three levels of protein intake. J Gerontol A Biol Sci Med Sci. 2001 Nov;56(11):M724-730

2. Phinney SD: The assessment of protein nutrition in the hospitalized patient. Clin Lab Med. 1981;1:767-774

3. Konstantinides FN, Kostantinides NN, Li JC, Myaya ME, Cerra FB: Urinary urea nitrogen: too insensitive for calculating nitrogen balance studies in surgical clinical nutrition. J Parenter Enteral Nutr. 1991 Mar-Apr;15(2):189-193

4. Borowitz D, Konstan MW, O'Rourke A, Cohen M, Hendeles L, Murray FT: Coefficients of fat and nitrogen absorption in healthy subjects and individuals with cystic fibrosis. J Pediatr Pharmacol Ther. 2007 Jan-Mar;12(1):47-52. doi: 10.5863/1551-6776-12.1.47

5. Dickerson RN: Nitrogen balance and protein requirements for critically ill older patients. Nutrients. 2016;8(4):226. doi: 10.3390/nu8040226

Special Instructions
Library of PDFs including pertinent information and forms related to the test

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

The nitrogen analyzer utilizes the Dumas combustion method of determining total nitrogen in urine.(Unpublished Mayo method)

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.

Friday

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.

1 to 8 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

1 week

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 was developed, and its performance characteristics 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
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.

84999

LOINC® Information

Test Id Test Order Name Order LOINC Value
NITU Nitrogen, Total, U 2660-9
Result Id Test Result Name Result LOINC Value
Result LOINC Value Tooltip
17418 Nitrogen, Total, U 2660-9
DUR8 Collection Duration 13362-9
TOTV Specimen Volume 28009-9

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