Normal absorption of fat (lipid) requires the presence of bile from the gallbladder or liver, pancreatic enzymes, and a normal gut. When a patient has a normal diet, the amount of fat excreted in the stool should represent no more than 20% of the total stool solids. There are a variety of fats, or lipids, that are excreted in the stool. They consist mainly of the lipids of the cells detached from the intestine, of the lipids of the diet that have not been absorbed as well as of secretions of the gastrointestinal system. Under normal conditions, in which adequate amounts of bile and pancreatic enzymes are present, most of the dietary lipids are absorbed in the small intestine.
However, in cases of malabsorption, large amounts of this fat are excreted in the stool, a condition known as steatorrhea. Steatorrhea can also occur in conditions such as Crohn's disease, cystic fibrosis, and Whipple's disease.
Possible Interpretations of Abnormal Values
- Increase: Amyloidosis, beta-lipoprotein deficiency, bile salt deficiency, celiac disease, cystic fibrosis, diarrhea, diverticulitis, enteritis, hepatobiliary disease, hypogammaglobulinemia, increased peristalsis, ingestion of castor oil or mineral oil, intestinal fistula, lymphangiectasia, lymphoma, pancreatic disease (cancer, chronic pancreatitis, enzyme deficiency), postoperative (bowel resection), steatorrhea, Whipple's disease, Zollinger-Ellison syndrome.
- Decrease: Fat-free diet
Test results can be altered by taking barium, bismuth, castor oil, mineral oil, a high-fiber diet, taking fleas, or using suppositories.