Nitrogen, Total, Feces
Use
This test is useful for determining nitrogen balance, which is the difference between the amount of nitrogen ingested and the amount excreted in urine and feces. It is often used in conjunction with a 24-hour urine nitrogen measurement to assess nutritional status, especially in cases of protein malnutrition, and to evaluate protein catabolism. Elevated fecal nitrogen levels may indicate increased protein catabolism due to stress, trauma, or other factors. It is also a key marker in the evaluation of pancreatic function, as excessive fecal nitrogen levels can indicate pancreatic atrophy in chronic progressive pancreatitis.
Special Instructions
The entire stool collection is required for this test, and it must contain at least 5 grams of feces. Laxatives and enemas should not be used during the collection, as barium and boric acid can interfere with the test. The patient can store the sample at refrigerated temperature during the collection period.
Limitations
Both urine and fecal nitrogen measurements are necessary to accurately determine nitrogen balance. Fecal samples with visible blood may skew results due to hemoglobin's nitrogen content. Additionally, factors like burns and copious sputum production must be considered in nitrogen balance studies as they may cause nitrogen loss.
New York Approved
Methodology
Automated Analyzer (Clinical Chemistry)
Biomarkers
LOINC Codes
- 16141-4
- 13363-7
- 30078-0
- 16141-4
Result Turnaround Time
1-8 days
Related Documents
For more information, please review the documents below
Specimen
Stool
Volume
Entire collection (24, 48, 72, or 96 hours)
Minimum Volume
See Specimen Required
Container
Stool container; complies with shipping requirements, do not use other containers.
Collection Instructions
Send entire stool collection (at least 5 g of feces) frozen on dry ice in Mayo Clinic Laboratories-approved container. All containers must be sent together and the number of containers indicated on the labels.
Patient Preparation
Laxatives and enemas should not be used during collection as barium and boric acid interfere with test procedure.
Storage Instructions
Patient can store sample at refrigerate temperature during collection period.
Causes for Rejection
Urine and stool mixed
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 7 days |
| Frozen | 3 years |