FATF - Clinical: Fat, Feces

Test Catalog

Test ID: FATF    
Fat, Feces

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosing fat malabsorption due to pancreatic or intestinal disorders


Monitoring effectiveness of enzyme supplementation in certain malabsorption disorders

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Fecal lipids include monoglycerides, diglycerides, triglycerides, phospholipids, glycolipids, soaps, sterols, cholesteryl esters, and sphingolipids.


Steatorrhea (increased fecal excretion of fat) may reflect a number of pancreatic or intestinal disorders, including chronic pancreatitis with or without stone obstruction, cystic fibrosis, neoplasia, Whipple disease, regional enteritis, tuberculous enteritis, gluten-induced enteropathy (celiac disease), Giardia-associated enteropathy, sprue, or the atrophy of malnutrition.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.


> or =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

Interpretation Provides information to assist in interpretation of the test results

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.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

This test is not useful for differentiating among pancreatic diseases.


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 stool collection analysis is recommended.


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


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

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

1. Henderson AR, Rinker AD: Gastric, pancreatic, and intestinal function. In Tietz Textbook of Clinical Chemistry. Third edition. Edited by CA Burtis, ER Ashwood. Philadelphia, WB Saunders Company, 1999, pp 1293-1295

2. Modern Nutrition in Health and Disease.10th edition. Edited by ME Shils, M Shike, AC Ross, et al. Baltimore, MD, Lippincott Williams and Wilkins, 2006, pp 1143-1151,1227-1234

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