Test Code LAB392 Fat, Feces
Additional Codes
FATF
Useful 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
Mayo Clinic Laboratories in RochesterSpecimen 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-hour or 72-hour collection
Acceptable: Entire 24-hour or a minimum of 5 g from a 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 |
Specimen to be stored/transported at Frozen temp.
Reference Values
TIMED COLLECTION
≥18 years: 2-7 g fat/24 h
Reference values have not been established for patients who are younger than 18 years of age.
RANDOM COLLECTION
All ages: 0-19% fat
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 |
Interpretation
Excretion of more than 7 grams fat/24 hours, when on a diet of 100 to 150 g of fat, is suggestive of a malabsorption defect.
Abnormal results from a random specimen should be confirmed by submission of a timed collection.
Test values for timed fecal fat collections will be reported in terms of g/24 hours; the duration of the collection may be 24, 48, 72, or 96 hours. Test values for random fecal fat collections will be reported in terms of percent fat.
Coefficient of Fat Absorption (CFA) can be calculated as follows:
(grams fat consumed - grams of fat excreted) x 100
CFA = grams of fat consumed
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;400[1-2]:33-36)
Specimen Retention Time
7 daysReject Due To
Preservative, media, or charcoal | Reject |
Method Name
Nuclear Magnetic Resonance (NMR) Spectroscopy
Secondary ID
607701Forms
If not ordering electronically, complete, print, and send Gastroenterology and Hepatology Test Request (T728) with the specimen
Day(s) Performed
Monday through Saturday