Cystic fibrosis causes mucus to become thick and sticky. The mucus builds up and clogs passages in many of the body's organs, but mostly in the lungs and the pancreas. The thick and sticky mucus can block pancreatic enzymes from reaching the digestive system and prevent fat from being digested and absorbed. If the body is not able to digest fat, the fat comes out in stools that are large, greasy, and smelly.

Before having this test, you will eat a diet that contains specific amounts of fat. You will keep a record of foods you eat and you will collect samples of your stool. The samples are then sent to a lab where the stools are analyzed for both fat content and the presence of certain enzymes.

People who have been diagnosed with cystic fibrosis may have a stool analysis to see how well their pancreas is working and how well their bodies are digesting food. It may also be done when cystic fibrosis is suspected because of the following symptoms:

• Large, greasy, smelly stools
• Digestive problems
• Unexplained weight loss or failure to gain or maintain weight
• Developmental delays
• Repeated lung infections

Why It Is Done

A stool analysis is done to see how well the pancreas is working and if pancreatic enzymes are reaching the intestine. This test can help determine whether supplemental digestive enzymes are needed. For people who are currently taking digestive enzymes, this test can help determine whether they are taking the right amount.

Results

Increased fat in the stool or low enzyme levels can mean that a person has digestive or pancreatic problems.

What To Think About

Other diseases besides cystic fibrosis can cause fatty stools and pancreatic problems.

Complete the medical test information form (PDF)(What is a PDF document?) to help you prepare for this test.