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Test Code NBLD0037 Fat, Feces

Additional Codes

Mayo Test Code: FATF

Useful For

Diagnosing fat malabsorption due to pancreatic or intestinal disorders


Monitoring effectiveness of enzyme supplementation in certain malabsorption disorders

Performing Laboratory

Mayo Medical Laboratories in Rochester

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

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

Day(s) and Time(s) Performed

Monday through Saturday

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


Reject Due To








Preservative, media, or charcoal


Method Name

Nuclear Magnetic Resonance (NMR) Spectroscopy


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