Sign in →

Test ID NITU Nitrogen, Total, 24 Hour, Urine


Specimen Required


Container/Tube: Plastic, 10-mL urine tube (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-Collection and Transportation for 24-Hour Urine Specimens in Special Instructions for multiple collections.


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

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

Interpretation

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 trauma, 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.

Clinical Reference

1. Morse, MH, et al: 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, et al: Urinary urea nitrogen: too insensitive for calculating nitrogen balance studies in surgical clinical nutrition. J Parenter Enteral Nutr 1991;15:189-193

Day(s) and Time(s) Performed

Tuesday, Friday; 11 a.m.

Analytic Time

1 day

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

LOINC Code Information

Test ID Test Order Name Order LOINC Value
NITU Nitrogen, Total, U In Process

 

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

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