Fecal fatQuantitative 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.
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.
Food additives are substances that become part of a food product when they are added during the processing or making of that food. "Direct" food addi...Read Article Now Book Mark Article
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.
Malabsorption involves problems with the body's ability to take in (absorb) nutrients from food.Read Article Now Book Mark Article
Bile is a fluid that is made and released by the liver and stored in the gallbladder. Bile helps with digestion. It breaks down fats into fatty acid...Read Article Now Book Mark Article
Less than 7 g of fat per 24 hours.
What Abnormal Results Mean
Decreased fat absorption may be caused by:
- Biliary tumor
Cancer is the uncontrolled growth of abnormal cells in the body. Cancerous cells are also called malignant cells.Read Article Now Book Mark Article
A bile duct stricture is an abnormal narrowing, most often of the common bile duct. This is a tube that moves bile from the liver to the small intes...Read Article Now Book Mark Article
Celiac disease (sprue)
Celiac disease is an autoimmune condition that damages the lining of the small intestine. This damage comes from a reaction to eating gluten. This ...Read Article Now Book Mark Article
Pancreatitis is swelling of the pancreas. Chronic pancreatitis is present when this problem does not heal or recurs and does not improve, gets worse...Read Article Now Book Mark Article
Crohn disease is a disease where parts of the digestive tract become inflamed. It most often involves the lower end of the small intestine and the be...Read Article Now Book Mark Article
Cystic fibrosis is a disease that causes thick, sticky mucus to build up in the lungs, digestive tract, and other areas of the body. It is one of th...Read Article Now Book Mark Article
- Gallstones (cholelithiasis)
Gallstones are hard deposits that form inside the gallbladder. These may be as small as a grain of sand or as large as a golf ball.Read Article Now Book Mark Article
Pancreatic cancer is cancer that starts in the pancreas.Read Article Now Book Mark Article
Radiation enteritis is damage to the lining of the intestines (bowels) caused by radiation therapy, which is used for some types of cancer treatment....Read Article Now Book Mark Article
Short bowel syndrome (for example from surgery or an inherited problem)
Short bowel syndrome
Short bowel syndrome is a problem that occurs when part of the small intestine is missing or has been removed during surgery. Nutrients are not prop...Read Article Now Book Mark Article
- Small bowel bacterial overgrowth
Whipple disease is a rare condition that mainly affects the small intestine. This prevents the small intestine from allowing nutrients to pass into ...Read Article Now Book Mark Article
There are no risks.
Factors that interfere with the test are:
- Mineral oil
- Inadequate fat in diet prior to and during the stool collection
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.
Digestive system organs - illustration
The digestive system organs in the abdominal cavity include the liver, gallbladder, stomach, small intestine and large intestine.
Digestive system organs
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.