Test Code FATF Fat, Feces
Reporting Name
Fat, FUseful For
Diagnosing fat malabsorption due to pancreatic or intestinal disorders
Monitoring effectiveness of enzyme supplementation in certain malabsorption disorders
This test is not useful for differentiating among pancreatic diseases.
Performing Laboratory

Specimen Type
FecalNecessary Information
Length of collection period is required.
Specimen Required
Patient Preparation:
1. For 3 days prior to and during the collection period:
a. Patient should be on a fat-controlled diet (100-150 g fat per day).
b. No laxatives (particularly mineral oil and castor oil).
c. No synthetic fat substitutes (eg, Olestra) or fat-blocking nutritional supplements.
2. The use of diaper rash ointments will falsely elevate test results. Discontinue use during collection period.
3. Barium interferes with test procedure; a waiting period of 48 hours before stool collection analysis is recommended.
Supplies: Stool Containers - 24, 48, 72 Hour Kit (T291)
Container/Tube: Stool container complies with shipping requirements, do not use other containers.
Specimen Volume:
Preferred: Entire 48-, or 72-hour collection
Acceptable: Entire 24-hour or random collection
Collection Instructions:
1. All containers must be sent together.
2. The entire collection must contain at least 5 g of feces.
3. For a random collection, a minimum of 5 g (do not send entire collection) is required.
4. The number of containers sent should be indicated on the labels (1 of 4, for example).
Additional Information:
1. Patient can store sample at refrigerate temperature during collection period.
2. A separate order and collection should take place if stool bicarbonate, calcium, chloride, magnesium, osmolality, pH, potassium, sodium, or any microbiology testing is desired.
Specimen Minimum Volume
See Specimen Required
Specimen Stability Information
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Fecal | Frozen (preferred) | 180 days | |
Refrigerated | 180 days |
Reference Values
TIMED COLLECTION
≥18 years: 2-7 g fat/24 hours
Reference values have not been established for patients who are <18 years of age.
RANDOM COLLECTION
All ages: 0-19% fat
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
82710
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
FATF | Fat, F | 16142-2 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
STWT | Total Weight | 30078-0 |
DUR2 | Duration | 13363-7 |
PFAT | Percent Fat | 35745-9 |
TFAT | Total Fecal Fat/24 Hr | 16142-2 |
Clinical Reference
1. Van de Kamer JH: Total Fatty Acids in Stool. In: Seligson D, ed. Standard Methods of Clinical Chemistry. Vol 2. Academic Press; 1958:34-38
2. Ellefson RD, Caraway WT: Lipids and Lipoproteins. In: Tietz NW, ed. Fundamentals of Clinical Chemistry. 2nd ed. WB Saunders Co; 1976:474-541
3. Shils ME, Ross AC, Caballero B, Cousins RJ, eds: Modern Nutrition in Health and Disease.10th ed. Lippincott Williams and Wilkins; 2006:1143-1151
4. Shils ME, Ross AC, Caballero B, Cousins RJ, eds: Modern Nutrition in Health and Disease.10th edition. Lippincott Williams and Wilkins; 2006:1227-1234
5. Hart PA, Conwell DL: Diagnosis of exocrine pancreatic insufficiency. Curr Treat Options Gastroenterol. 2015 Sep;13:347-353. doi:10.1007/s11938-015-0057-8
Method Description
After the well-homogenized stool sample is weighed and dried, it is rolled in Teflon and placed in a nuclear magnetic resonance spectrometer (NMR). The NMR determines the percent of fat in the sample. The percent is then converted to grams fat/24 hours excretion or percent fat of random sample.(Korpi-Steiner NL, Ward JN, Kumar V, McConnell JP: Comparative analysis of fecal fat quantitation via nuclear magnetic resonance spectroscopy [1H NMR] and gravimetry. Clin Chim Acta. 2009 Feb;400[1-2]:33-36)
Reject Due To
Preservative, media, or charcoal | Reject |
Method Name
Nuclear Magnetic Resonance (NMR) Spectroscopy
Forms
If not ordering electronically, complete, print, and send a Gastroenterology and Hepatology Client Test Request (T728) with the specimen.