Lactose Intolerance
| Overview |
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- Lactose Intolerance is caused by a deficiency of lactase, an enzyme present on the small intestine epithelium's brush border, which digests the inabsorbable disaccharide 'Lactose' into the absorbable monosaccharides glucose and galactose (See: Carbohydrate Digestion and Absorption). Nearly all individuals express lactase as neonates in order to properly digest maternal milk; however, expression declines in many ethnicities with age. Lactose intolerance tends to be more frequent among African Americans.
| Pathogenesis |
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- Defective breakdown of lactose results in an inability to absorb the sugar. The unabsorbed sugar acts as an osmolyte, thus interfering with GI Water and Electrolyte Absorption in the intestinal lumen and consequently yielding an osmotic diarrhea.
| Morphology |
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- No morphological abnormalities of the mucosa are observed.
| Clinical Consequences |
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- Osmotic diarrhea following ingestion of milk or other dairy products.