Fecal Fat Test

Fecal Fat Test- Why am I having this test?

Fecal fat test is performed to determine whether a person has a condition that prevents him or her from absorbing foods well (malabsorption). It measures the presence of fat in the stool (steatorrhea). Malabsorption can be present in conditions like Crohn disease, cystic fibrosis, and short gut syndrome.

What is being tested?

In this test, a sample of stool (feces) is checked to see how much fat it contains. If your stool contains a lot of fat, this usually indicates that fat is going through your body at an increased rate. This is a possible sign of malabsorption.

What kind of sample is taken?

A stool sample is collected in a germ-free (sterile) container that is given to you by the lab.

How do I collect samples at home?

When collecting a stool sample at home, make sure you:

  • Use supplies and instructions that you received from the lab.
  • Have a bowel movement directly into a clean, dry container. Do notcollect stool from the water in the toilet.
  • Transfer the sample into the sterile cup that you received from the lab.
  • Do notlet any toilet paper or urine get into the cup.
  • Wash your hands with soap and water after collecting the sample.
  • Return the sample(s) to the lab as instructed.

How do I prepare for this test?

Your health care provider may ask you to eat 100 grams of fat per day for three days before and throughout the period of stool collection. The grams of fat suggested are lower for infants and children. Do notuse laxatives or enemas during the period of stool collection. You may be asked to provide samples of all your stools over a period of hours (timed collection) or a single sample (random collection).

How are the results reported?

Your test results for the timed collection will be reported as a value that tells you how many grams of fat were in your stool. Your health care provider will compare your results to normal ranges that were established after testing a large group of people (reference ranges). Reference ranges may vary among labs and hospitals. For this test, common reference ranges are:

  • Timed collection:
    • 18 years old or older: 2–6 grams of fat over 24 hours.
    • Younger than 18 years old: Reference values have not been established for this group.
  • For a single sample, your results may be reported as positive or negative for excess fat (qualitative).

What do the results mean?

Levels of fecal fat above the normal range may indicate:

  • Cystic fibrosis.
  • Malabsorption due to diseases such as celiac disease, Crohn disease, or radiation enteritis.
  • Poor digestion due to obstructions in the pancreas or bile ducts.
  • Short gut syndrome.

Talk with your health care provider about what your results mean.

Questions to ask your health care provider

Ask your health care provider, or the department that is doing the test:

  • When will my results be ready?
  • How will I get my results?
  • What are my treatment options?
  • What other tests do I need?
  • What are my next steps?


  • Fecal fat test is a test that measures the amount of fat in stool in order to determine whether a person has a condition that prevents absorption of food in the intestines.
  • Your health care provider may ask you to collect stool samples at home. Follow instructions from your health care provider or your lab on how to do a proper collection at home.
  • Higher-than-normal levels of fat in the stool may indicate cystic fibrosis or other diseases that affect the body’s ability to absorb nutrients.
  • Talk with your health care provider about what your results mean.

Sign up to receive the trending updates and tons of Health Tips

Join SeekhealthZ and never miss the latest health information

Scroll to Top