Health Library

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.

Images

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 (g) 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 a normal small intestine.

Normal Results

Less than 7 g of fat per 24 hours.

What Abnormal Results Mean

Decreased fat absorption may be caused by:

• Biliary tumor
• Biliary stricture
• Celiac disease (sprue)
• Chronic pancreatitis
• Crohn disease
• Cystic fibrosis
• Gallstones (cholelithiasis)
• Pancreatic cancer
• Pancreatitis
• Radiation enteritis
• Short bowel syndrome (for example from surgery or an inherited problem)
• Small bowel bacterial overgrowth
• Whipple disease

Risks

There are no risks.

Considerations

Factors that interfere with the test are:

• Enemas
• Laxatives
• Mineral oil
• Inadequate fat in diet prior to and during the stool collection

Related Information

References

Huston CD. Intestinal protozoa. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 113.

Semrad CE. Approach to the patient with diarrhea and malabsorption. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 131.

Siddiqui UD, Hawes RH. Chronic pancreatitis. In: Chandrasekhara V, Elmunzer JB, Khashab MA, Muthusamy RV, eds. Clinical Gastrointestinal Endoscopy. 3rd ed. Philadelphia, PA: Elsevier; 2019:chap 59.

Review Date: 7/30/2022  

Reviewed By: Michael M. Phillips, MD, Emeritus Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

A.D.A.M., Inc. is accredited by URAC, for Health Content Provider (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics. This site complies with the HONcode standard for trustworthy health information: verify here.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- 2024 A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.