It is well-documented that Alagille syndrome affects multiple organs, such as the liver, heart, kidneys and skeleton, but we are just starting to explore how it affects the pancreas. Researchers previously thought that the poor growth and malnutrition associated with this disorder were only a result of bile flow stoppage (also called cholestasis), which in turn contributes to the body's inability to absorb fat. Now medical professionals are beginning to realize that the pancreas may also be playing a role in fat malabsorption in AGS.
The pancreas is important for the digestion and absorption of nutrients. It is made up of two separate parts, each with a unique function. The first, the endocrine pancreas, makes hormones — including insulin and glucagon — that help regulate the body's sugar balance. The second part, known as the exocrine pancreas, makes enzymes that help digest food and release the bicarbonate that neutralizes stomach acid. If the pancreas is not making enough of these enzymes and acid buffers, a person is said to be pancreatic insufficient.
Children who are pancreatic insufficient do not properly absorb fat from food, which is called fat malabsorption, and excrete fat in their stools. Stools of children with fat malabsorption are often loose, greasy and not well-formed. Based upon past and ongoing studies of Alagille patients, we estimate between 30 and 40 percent of children with Alagille syndrome are pancreatic insufficient, which may, in turn, contribute to their poor nutrition and growth.
Pancreatic exocrine function can help determine if your child is pancreatic insufficient; it can be tested both directly and indirectly.
A healthy child older than 6 months should absorb more than 93 percent of his or her dietary fat. It is not abnormal for healthy infants to excrete up to 15 percent of dietary fat. If a child is absorbing less than 93 percent, he or she is said to be fat-malabsorbing. Pancreatic insufficiency is one cause of fat malabsorption. Liver disease can also be a contributing factor.
If tests determine your child is pancreatic insufficient, he or she will receive pancreatic enzyme supplementation. Pancreatic enzymes supplements, taken before meals, help to digest or break down food so the body can absorb nutrients.
Doctors can indirectly assess pancreatic function with a 72-hour stool collection, in combination with a three-day dietary record, to determine how much fat a child is absorbing from the food he or she is eating. Because this collection is usually done at home, you will be given the supplies and instructions you need. All stools are collected in pre-weighed containers for 72 hours and frozen. Everything your child eats during these three days must be weighed and recorded. The laboratory then determines the amount of fat absorbed (coefficient of fat absorption). Unfortunately, this test cannot distinguish between fat malabsorption due to liver disease and fat malabsorption due to pancreatic diseases.
Reviewed by: Binita M. Kamath, MD
Date: January 2009