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Test ID NITF Nitrogen, Total, Feces

Reporting Name

Nitrogen, Total, F

Useful For

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

 

Assessing nutritional status (protein malnutrition)

 

Evaluating protein catabolism

Specimen Type

Fecal


Shipping Instructions


Send entire stool collection (must contain at least 5 g of feces) frozen on dry ice in Mayo Medical Laboratories-approved container.



Necessary Information


Length of collection period is required.



Specimen Required


Patient Preparation: Laxatives and enemas should not be used during collection.

Supplies: Stool Containers - 24, 48, 72 Hours Kit (T291)

Container/Tube: Stool container (T291); complies with shipping requirements, do not use other containers.

Specimen Volume: Entire collection (24, 48, 72, or 96 hour)

Collection Instructions:

1. Entire collection must be submitted which should contain at least 5g to 10 g of feces.

2. See Stool Collection Information Sheet in Special Instructions

Additional Information: Barium and boric acid interfere with test procedure.


Specimen Minimum Volume

2.5 g

Specimen Stability Information

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

Reference Values

<16 years: not established

≥16 years: 1-2 g/24 hours

Day(s) and Time(s) Performed

Tuesday, Friday; 11 a.m.

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
NITF Nitrogen, Total, F In Process

 

Result ID Test Result Name Result LOINC Value
17417 Nitrogen, Total, F 16141-4
DUR9 Collection Duration 13363-7
17416 Total Weight 30078-0

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.

Interpretation

Average fecal nitrogen excretion is approximately 1 to 2 g N/24 hours. Significantly abnormal excretion rates, resulting in negative nitrogen balance, may be associated with severe stress due to multiple trauma, head injury, sepsis, or extensive burns. Elevated values above 2.5 g N/24 hours may be consistent with chronic progressive pancreatitis. The goal with therapy for a depleted person is a positive nitrogen balance of 4 to 6 g N/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

Analytic Time

1 day

Method Name

Dumas Combustion