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Test Code 0203539 Fat, Feces

Additional Codes

Mayo Test ID

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Diagnosing fat malabsorption due to pancreatic or intestinal disorders


Monitoring effectiveness of enzyme supplementation in certain malabsorption disorders

Method Name

Nuclear Magnetic Resonance (NMR) Spectroscopy

Reporting Name

Fat, F

Specimen Type


Necessary 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 Hours Kit (T291)

Container/Tube: Stool container (T291); 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

5 g

Specimen Stability Information

Specimen Type Temperature Time
Fecal Frozen (preferred) 180 days
  Refrigerated  180 days

Reject Due To








Preservative, media, or charcoal


Reference Values


≥18 years: 2-7 g fat/24 hours

Reference values have not been established for patients who are <18 years of age.



All ages: 0-19% fat


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

Day(s) and Time(s) Performed

Monday through Saturday

Analytic Time

1 day

Specimen Retention Time

7 days

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


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 % Fat 35745-9
TFAT Total Fat/24 Hr 16142-2


If not ordering electronically, complete, print, and send a Gastroenterology and Hepatology Client Test Request (T728) with the specimen.