Understanding a Fecal Fat Study

Background on Malabsorption and Pancreatic Insufficiency

Cystic fibrosis is a genetic disease in which a faulty protein in a person's genes causes their body to produce abnormally thick, sticky mucus For some people with CF, this mucus causes mainly respiratory complications such as chronic bronchitis, sinusitis or recurring pneumonia. However, CF is not just a respiratory disease. The thick mucus is also present in the person's digestive system, where it prevents the pancreas from secreting the enzymes needed to absorb nutrients and energy from food. When a person experiences malabsorption due to the lack of naturally produces pancreatic enzymes, that person is said to be pancreatic insufficient.

One of the ways to determine whether a person with cystic fibrosis will need supplemental pancreatic enzymes is to do what's called a "fecal fat study." Additionally, a fecal fat study can help the doctor or dietician determine which type of pancreatic enzyme supplements to prescribe, and how many pills are to be taken with food.

Fecal Fat

Not all fats are bad. In fact, the body relies on certain types of fat to store energy, and help absorb vitamins A, D, E and K. A person with normal pancreatic and liver function readily absorbs dietary fat from digested food as it passes into the small intestine. The small intestine is the last stop before foods become fecal matter. The technical term for fatty stool is "steatorrhea."

When the body is unable to absorb fat from food, the fat gets passed through the body and ends up in a person's stool or bowel movement (BM.) Too much fat in the stool can cause BMs to float, have a bad odor, or be loose and oily. People who are pancreatic insufficient or who have pancreatitis may experience a great deal of pain, bloating and gas when they eat foods that are high in fats.

The Fecal Fat Study

A fecal fat study begins by the patient maintaining a diet high in fat (at least 100 grams per day) for three days. Then, the patient is to collect his or her bowel movements for three days (72 hours.) A laboratory technician or your family doctor will provide the container you will use to collect the sample. When three days of collection are complete, the sample is brought to the lab where it will be dried, and initially weighed. The sample will then be subject to a process by which the fats are separated from the rest of the fecal material. The fat is then weighed and compared to the total weight of the initial sample. This is used to calculate a percentage or amount of fat per day that was excreted in the stool. In healthy individuals, fat is expected to make up about 5% of the total fecal material. In patients with CF, this percentage is much higher. These patients are said to be pancreatic insufficient.

The Results

People who are pancreatic insufficient as determined by a fecal fat study require supplemental digestive enzymes in order to maintain healthy nutritional status. Fats and proteins are essential to proper growth and development. In patients with cystic fibrosis, the pancreas is blocked and cannot secrete amylase, lipase, trypsin and chymotrypsin, which are necessary to absorb not only fats, but proteins as well.Supplemental pancreatic enzymes are formulated in such a way that they contain three specific types of digestive enzymes that help the body absorb fats and proteins. The manufacturers of enzyme supplements combine the three types of enzymes in different ratios. Each supplement is formulated this way.