Steatorrhea overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Steatorrhea is the formation of non-solid feces. Stools may also float due to excess fat from malabsorption, have an oily appearance and be foul smelling. An oily anal leakage or some level of fecal incontinence may occur. There is increased fat excretion, which can be measured by determining the fecal fat level. While definitions have not been standardized, fat excretion in feces in excess of 0.3 (g/kg) / day is considered indicative of steatorrhea.
Historical Perspective
Classification
Steatorrhea may be classified based on etiology into 3 types, intestinal, biliary, and pancreatic steatorrhea.
Pathophysiology
Normal fat absorption involves a complex mixture of digestive enzymes, bile salts, and an intact intestinal mucosa to enable uptake of these hydrophobic complexes.
- After ingestion, dietary lipids are initially emulsified in the stomach and then hydrolyzed by the action of gastric and pancreatic lipase and colipase.
- The hydrolyzed lipids are then aggregated into micelles or liposomes with the addition of bile salts in the duodenum and jejunum.
- These micelles are absorbed across the intact intestinal villi by both active and passive processes. Finally, they are packaged into chylomicrons within intestinal epithelial cells and transported to the circulation via the lymphatic system
- More than 90% of daily dietary fat is absorbed into the general circulation, but any defects in the processes can reduce this uptake and lead to fatty diarrhea/ steatorrhea.
- The bulk of dietary lipid is neutral fat or triglyceride, composed of a glycerol backbone with each carbon linked to a fatty acid.
- Foodstuffs typically also contain phospholipids, sterols like cholesterol and many minor lipids, including fat-soluble vitamins.
- Finally, small intestinal contents contain lipids from sloughed epithelial cells and considerable cholesterol delivered in bile.
Causes
Common causes of steatorrhea
- Celiac disease
- Choledocholithiasis
- Cystic fibrosis
- Exocrine pancreatic insufficiency
- Hypolipidemic drugs
- Inflammatory bowel disease
- Small bowel bacterial overgrowth syndrome
Differentiating steatorrhea from other Diseases
Steatorrhea must be differentiated from Cystic fibrosis, Hartnup'sdisease, Whipple's disease, Zollinger Ellison syndrome, Acrodermatitis enteropathica, intestinal lymphangiectasia
Epidemiology and Demographics
The demographic measures of steatorrhea can be explained by independent causes of steatorrhea.
Celiac disease
Incidence
- The incidence of celiac disease is approximately 10-13 per 100,000 individuals worldwide.
- In United States the incidence of celiac disease is approximately 10 per 100,000 individuals
Prevalence
- Worldwide, the prevalence of celiac disease is estimated to be 500 to 1000 per 100,000 individuals.
- In United States, the prevalence of celiac disease is approximately 710 per 100,000 individual
Age
- Celiac disease affects children and adults alike.
- In children celiac disease peaks in early childhood.
- In adults celiac disease is usually diagnosed around fourth and fifth decades of life.
Race
- Celiac disease usually affects individuals of the non-Hispanic white race (1000 per 100,000 individuals), Hispanics (300 per 100,000 individuals) and non-Hispanic blacks (200 per 100,000 individuals).
- HLA-DQ2 associated celiac disease is frequently found in white populations located in Western Europe.