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Test Code FATF Fat, Feces

Reporting Name

Fat, F

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 Rochester

Specimen Type

Fecal


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 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

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

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

82710

Clinical Information

Total fecal lipids include glycerides, phospholipids, glycolipids, soaps, sterols, cholesteryl esters, and sphingolipids. Excess fecal fat in feces, (steatorrhea) is indicative of malabsorption disorders, such as pancreatic insufficiency or Whipple disease. Therefore, measurement of the fecal fats can be useful in establishing a diagnosis of such pancreatic diseases as cystic fibrosis, chronic pancreatitis, neoplasia, or stone obstruction and such intestinal diseases as Whipple disease, regional enteritis, tuberculous enteritis, gluten-induced enteropathy (also called celiac disease or sprue), and the atrophy of malnutrition.

 

Distinguishing free fatty acids from neutral fats, once thought to be helpful in the differential diagnosis of pancreatic disease, has fallen out of favor. Note that the composition of fats in the feces, normally predominately free fatty acids, can change significantly to predominately neutral fatty acids when the patient is on orlistat. This test does not distinguish between free and neutral fatty acids.

Reject Due To

Preservative, media, or charcoal Reject

Method Name

Nuclear Magnetic Resonance (NMR) Spectroscopy

Forms

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

Day(s) Performed

Monday through Saturday

Report Available

1 to 3 days