In fecal fat test, stool samples are collected for 3 days and then analyzed for their fat (lipid) content. Normally, most dietary fat is absorbed by the small intestine (small bowel). Excessive amounts of lipids in the stool indicate improper absorption of fat due to an abnormality in the lining of the small bowel, or improper digestion of fat caused by a problem with the bile acids or digestive enzymes secreted by the pancreas or liver.
Purpose of the Fecal Fat Test
- To confirm the diagnosis of steatorrhea (excessive excretion of fecal lipids) in people with large, greasy, foul-smelling stools or diarrhea
- To assess liver, gallbladder, pancreas and intestine function indicated by fat absorption
Who Performs Fecal Fat Test
- A laboratory technician
Special Concerns about Fecal Fat Test
- Don’t use a container with a waxy coating to collect the stool samples. The wax may mix with the sample and interfere with the test results.
- Don’t take laxatives or mineral oil or use enemas during the test period.
Before the Fecal Fat Test
- Inform your doctor if you regularly take any medications. Certain drugs may affect fecal fat levels and must be discontinued briefly before the test.
- For 3 days before the testand throughout the testing periodyou should ingest at least 100 grams of fat per day.
- Avoid alcohol and any products with the fat substitute olestra.
What You Experience during Fecal Fat Test
- Collect all of your stool in a dry, clean container over the testing period of 3 days. You will either be given one large container or several smaller containers for each sample.
- Be careful not to contaminate the samples with urine or toilet paper.
- Keep the containers refrigerated and tightly closed between samples.
Risks and Complications of Fecal Fat Test
- There are no risks or complications associated with this test.
After the Fecal Fat Test
- Label the containers with name, time, and date then take the stool specimens to a laboratory.
- Resume your normal diet and any medications withheld before the test.
Results of Fecal Fat Test
- The fat content of your stool is calculated. If the test is positive for steatorrhea, a wide variety of conditions may be responsible, including bile duct obstructions, pancreatic disease, and inflammatory intestinal disorders such as Crohn’s disease.
- Further tests, such as an upper GI series, will be necessary to determine the cause of steatorrhea.
The Johns Hopkins Consumer Guide to Medical Tests
Simeon Margolis, M.D., Ph.D., Medical Editor
Updated by Remedy Health Media