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Test ID NITU Nitrogen, Total, 24 Hour, Urine

Useful For

Assessing nutritional status (protein malnutrition)

 

Evaluating protein catabolism

 

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

Method Name

Dumas Combustion

Reporting Name

Nitrogen, Total, U

Specimen Type

Urine

Container/Tube: Plastic, 10-mL urine tube (Supply T068)

Specimen Volume: 10 mL

Collection Instructions:

1. Collect urine for 24 hours.

2. No preservative.

Additional Information:

1. 24-Hour volume is required.

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

 

Urine Preservative Collection Options

Ambient

Yes

Refrigerated

Yes

Frozen

Preferred

6N HCl

Yes

50% Acetic Acid

Yes

Na2CO3

Yes

Toluene

Yes

6N HNO3

No

Boric Acid

No

Thymol

Yes

 

Specimen Minimum Volume

2 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Refrigerated (preferred) 7 days
  Ambient  7 days
  Frozen 

Clinical Information

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

<16 years: not established

≥16 years: 4-20 g/24 hours

Cautions

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.

Day(s) Performed

Tuesday, Friday; 11 a.m.

Report Available

1 day

Performing Laboratory

Mayo Medical Laboratories in Rochester

Test Classification

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 U.S. Food and Drug Administration.

CPT Code Information

84999

NY State Approved

Yes