Home
HelpTest ID NITF Nitrogen, Total, Feces
Reporting Name
Nitrogen, Total, FUseful For
Determining nitrogen balance, when used in conjunction with 24-hour urine nitrogen measurement
Assessing nutritional status (protein malnutrition)
Evaluating protein catabolism
Specimen Type
FecalShipping Instructions
Send entire stool collection (must contain at least 5 g of feces) frozen on dry ice in Mayo Clinic Laboratories-approved container.
Necessary Information
Length of collection period is required.
Specimen Required
Patient Preparation: Laxatives and enemas should not be used during collection as barium and boric acid interfere with test procedure.
Supplies: Stool Containers - 24, 48, 72 Hour Kit (T291)
Container/Tube: Stool container; complies with shipping requirements, do not use other containers.
Specimen Volume: Entire collection (24, 48, 72, or 96 hours)
Collection Instructions:
1. All containers must be sent together.
2. Entire collection must contain at least 5 g of feces.
3. The number of containers sent should be indicated on the labels (ie, 1 of 4)
Specimen Stability Information: Frozen 3 years
Additional Information: Patient can store sample at refrigerate temperature during collection period.
Specimen Minimum Volume
See Specimen Required
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Fecal | Frozen (preferred) | ||
| Ambient | 7 days | ||
| Refrigerated | 7 days | ||
Reference Values
<16 years: Not established
≥16 years: 1-2 g/24 hours
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
84999
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 protein catabolism; therefore, urine and fecal nitrogen concentrations 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 levels.
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 (N) 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 traumas, 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.
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.
Fecal samples with visible blood may exhibit a positive bias for nitrogen due to the contribution of nitrogens present within hemoglobin.
Clinical Reference
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;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;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;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
Method Description
The nitrogen analyzer utilizes the Dumas combustion method of determining total nitrogen in feces.(Unpublished Mayo method)
Reject Due To
| Urine and stool mixed | Reject |
NY State Approved
YesMethod Name
Dumas Combustion
Day(s) Performed
Friday