Test Directory

Fat, Feces

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Updated Test Information:

Test Description
Fat, Feces

Fat, Feces, Random; Fecal Fat; Fecal Fat, Quantitative; Fecal Fat, Random; Lipids, Stool; Stool, Fat; Coefficient of Fat Absorption (CFA); Fecal Fat, Timed; FATF

Test ID
General Information

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 Type


Specimen Requirements

  • Preferred: 48- or 72-Hr stool collection

  • Acceptable: 24-Hr stool collection

  • Acceptable: random stool

Specimen Collection / Processing Instructions

For 3 days prior to and during the collection period:

  • Patient should be on a fat-controlled diet (100-150 g fat per day)

  • No laxatives (particularly mineral oil and castor oil)

  • No synthetic fat substitutes (eg, Olestra) or fat-blocking nutritional supplements

  • The use of diaper rash ointments will falsely elevate test results. Discontinue use during collection period

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

Required Information

Length of collection period is required


  • Frozen (preferred): 180 days

  • Refrigerated: 180 days

Unacceptable Specimen Conditions

Preservative, media, or charcoal


  • Proper patient preparation is critical (see Specimen Required). 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.


Nuclear Magnetic Resonance (NMR) Spectroscopy

Estimated TAT

1-3 days

Testing Schedule



7 days

CPT Code(s)


Additional Information
Minimum Sample Volume

5 g

Reference Range

≥ 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

Performing Lab


LOINC Code(s)

30078-0, 13363-7, 35745-9, 16142-2