Health Information

Fecal fat

Fecal fat


Quantitative stool fat determination; Fat absorption

The fecal fat test measures the amount of fat in the stool. This can help gauge the percentage of dietary fat that the body does not absorb.

I Would Like to Learn About:

  • How the Test is Performed

    There are many ways to collect the samples.

    • For adults and children, you can catch the stool on plastic wrap that is loosely placed over the toilet bowl and held in place by the toilet seat. Then put the sample in a clean container. One test kit supplies a special toilet tissue that you use to collect the sample, then put the sample in a clean container.
    • For infants and children wearing diapers, you can line the diaper with plastic wrap. If the plastic wrap is placed properly, you can prevent mixing of urine and stool. This will provide a better sample.

    Collect all stool that is released over a 24-hour period (or sometimes 3 days) in the containers provided. Label the containers with name, time, and date, and send them to the lab.

  • How to Prepare for the Test

    Eat a normal diet containing about 100 grams of fat per day for 3 days before starting the test. The health care provider may ask you to stop using drugs or food additives that could affect the test.

  • How the Test will Feel

    The test involves only normal bowel movements. There is no discomfort.

  • Why the Test is Performed

    This test evaluates fat absorption to tell how well the liver, gallbladder, pancreas, and intestines are working.

    Fat malabsorption can cause a change in your stools called steatorrhea. To absorb fat normally, the body needs bile from the gallbladder (or liver if the gallbladder has been removed), enzymes from the pancreas, and normal intestines.

  • Normal Results

    Less than 7 grams of fat per 24 hours.

  • What Abnormal Results Mean

    Decreased fat absorption may be caused by:

    • Biliary cancer
    • Biliary stricture
    • Celiac disease
    • Chronic pancreatitis
    • Crohn's disease
    • Cystic fibrosis
    • Gallstones (cholelithiasis)
    • Pancreatic cancer
    • Pancreatitis
    • Radiation enteritis
    • Short bowel syndrome (e.g., from surgery or an inherited problem)
    • Sprue
    • Whipple's disease
  • Risks

    There are no risks.

  • Considerations

    Factors that interfere with the test are:

    • Enemas
    • Laxatives
    • Mineral oil

Related Information

  MalabsorptionBileCancerBiliary stricture...Celiac disease - s...GallstonesChronic pancreatit...Crohn's diseaseCystic fibrosisPancreatic cancer...     Gallstones and gal...Crohn disease


Hogenauer C, Hammer HF. Maldigestion and malabsorption. In: Feldman M, Friedman LS, Sleisenger MH, eds. Sleisenger & Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, PA: Elsevier Saunders; 2010:chap 101.

Semrad CE, Powell DW. Approach to the patient with diarrhea and malabsorption. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 142.


Review Date: 8/19/2014  

Reviewed By: Jenifer K. Lehrer, MD, Department of Gastroenterology, Frankford-Torresdale Hospital, Aria Health System, Philadelphia, PA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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