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25443 Fat, Feces (FATF)

Fat, Feces (FATF)
Test Code: FATFSO
Synonyms/Keywords
​Fat, Feces, Random, Fecal Fat, Fecal Fat, Quantitative, Fecal Fat, Random, Lipids, Stool, Stool, Fat, Coefficient of Fat Absorption (CFA), Fecal Fat, Timed, 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.

Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
​No ​ ​Entire 48 or 72 hour collection ​Mayo fecal Fat collection container(s) (supply T291) ​24 hour collection is acceptable

​All container(s) must be sent (number of containers should be indicated on the label {1 of 4, etc})

5 g of feces

​Random collection ​Mayo fecal Fat collection container (supply T291) ​Sterile container ​5 g (do not send entire collection) ​5 g
Collection Processing Instructions

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.

Must use Mayo collection containers (supply T291) provided by Marshfield Labs.

Length of collection period is required.

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 Stability Information
Specimen Type Temperature Time
​Feces ​ ​Frozen (preferred) ​180 days
​Refrigerate ​180 days
Rejection Criteria

Preservative, media, or charcoal

Interference

​Proper patient preparation is critical. Failure to adhere to a fat-controlled diet or to exclude other oils or oil substitutes from the diet may make interpretation difficult.

Barium interferes with test procedure; a waiting period of 48 hours before fecal collection is recommended.

The use of charcoal as a marker is not recommended. If charcoal is used, please notify the laboratory.

Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Mayo Clinc Laboratories​ ​Monday through Saturday ​1-3 days ​Nuclear Magnetic Resonance (NMR) Spectroscopy
Reference Lab
Test 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.

Reference Range Information
Performing Location Reference Range
Mayo Clinic Laboratories​ ​

​Timed Collection: >=18 years: 2-7 g fat/24 hours

Reference Values have not been established for patients who are less than 18 years of age.

​Random Collection: All ages: 0-19%
Interpretation

​Excretion of >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

Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
82710​ ​1
Synonyms/Keywords
​Fat, Feces, Random, Fecal Fat, Fecal Fat, Quantitative, Fecal Fat, Random, Lipids, Stool, Stool, Fat, Coefficient of Fat Absorption (CFA), Fecal Fat, Timed, FATF
Ordering Applications
Ordering Application Description
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
​No ​ ​Entire 48 or 72 hour collection ​Mayo fecal Fat collection container(s) (supply T291) ​24 hour collection is acceptable

​All container(s) must be sent (number of containers should be indicated on the label {1 of 4, etc})

5 g of feces

​Random collection ​Mayo fecal Fat collection container (supply T291) ​Sterile container ​5 g (do not send entire collection) ​5 g
Collection Processing

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.

Must use Mayo collection containers (supply T291) provided by Marshfield Labs.

Length of collection period is required.

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 Stability Information
Specimen Type Temperature Time
​Feces ​ ​Frozen (preferred) ​180 days
​Refrigerate ​180 days
Rejection Criteria

Preservative, media, or charcoal

Interference

​Proper patient preparation is critical. Failure to adhere to a fat-controlled diet or to exclude other oils or oil substitutes from the diet may make interpretation difficult.

Barium interferes with test procedure; a waiting period of 48 hours before fecal collection is recommended.

The use of charcoal as a marker is not recommended. If charcoal is used, please notify the laboratory.

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.

Reference Range Information
Performing Location Reference Range
Mayo Clinic Laboratories​ ​

​Timed Collection: >=18 years: 2-7 g fat/24 hours

Reference Values have not been established for patients who are less than 18 years of age.

​Random Collection: All ages: 0-19%
Interpretation

​Excretion of >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

For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Mayo Clinc Laboratories​ ​Monday through Saturday ​1-3 days ​Nuclear Magnetic Resonance (NMR) Spectroscopy
Reference Lab
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
82710​ ​1
For most current information refer to the Marshfield Laboratory online reference manual.