Disaccharidase Deficiency: Definition and Clinical Significance
Disaccharidase deficiency is a condition characterized by reduced activity of enzymes in the small intestinal brush border that are essential for breaking down disaccharides (such as lactose, sucrose, maltose, isomaltose, and trehalose) into monosaccharides, leading to carbohydrate malabsorption and gastrointestinal symptoms including abdominal pain, bloating, flatulence, and diarrhea. 1
Types and Prevalence
- Disaccharidase deficiencies can affect various enzymes including lactase, sucrase, maltase, palatinase, and glucoamylase, with lactase deficiency being the most common 2
- These deficiencies can be isolated (affecting a single enzyme) or present as multiple enzyme deficiencies, with some patients experiencing pan-disaccharidase deficiency (deficiency in 3 or more enzymes) 3
- Studies show that disaccharidase deficiency is more common than previously thought in adults with chronic gastrointestinal symptoms, with prevalence rates of:
- In a Russian study, lactase deficiency was detected in 86.5% of patients with functional bowel disorders, while glucoamylase deficiency was found in 84.1%, sucrase deficiency in 50%, and maltase deficiency in 48.7% 5
Etiology
Disaccharidase deficiencies can be classified as:
- Primary (congenital/genetic): Present from birth due to genetic mutations affecting enzyme production 1
- Secondary (acquired): Develops as a consequence of other gastrointestinal conditions or factors that damage the intestinal brush border 1, 2
Clinical Presentation
- Common symptoms include abdominal pain, bloating, flatulence, diarrhea, and in some cases weight loss 1, 2
- Patients with pan-disaccharidase deficiency may experience more weight loss compared to those with single enzyme deficiency 2
- Symptoms significantly overlap with irritable bowel syndrome (IBS) and other functional gastrointestinal disorders, making diagnosis challenging 2, 5
- No single symptom has been found to be more prevalent in patients with confirmed enzyme deficiency compared to those without deficiency 3
Diagnosis
- The gold standard for diagnosis is measurement of disaccharidase activity in small intestinal biopsy samples obtained during endoscopy 1, 2
- For lactase deficiency specifically, lactose breath testing can be used with a sensitivity of 78.3% and specificity of 72.0% 4
- Fecal elastase testing may be used to rule out exocrine pancreatic insufficiency, which can present with similar symptoms 6
Differential Diagnosis
Conditions with overlapping symptoms include:
- Celiac disease 6
- Small intestinal bacterial overgrowth 6
- Inflammatory bowel disease 6
- Exocrine pancreatic insufficiency 6
- Bile acid diarrhea 6
- Infectious etiologies such as giardiasis 6
Management
- Dietary modification is the first-line treatment, involving restriction of specific disaccharides based on the enzyme deficiency identified 2
- Enzyme replacement therapy has shown effectiveness in treating symptoms 2
- For patients with lactase deficiency, lactose restriction or lactase supplements may be beneficial 1
- For patients with sucrase deficiency, limiting sucrose intake or using sucrase enzyme supplements may help 1
- Patients who do not respond to traditional treatments for functional bowel disorders may benefit from testing for disaccharidase deficiency 2
Clinical Considerations
- Disaccharidase deficiency is often underdiagnosed in adults with chronic gastrointestinal symptoms 2
- Patients with irritable bowel syndrome who do not respond to low FODMAP dietary restriction may have undiagnosed disaccharidase deficiency 2
- In infants younger than 12 months, digestive enzymes like amylase may not be fully functional, which can affect carbohydrate digestion 6
- Disaccharidase deficiency should be considered in the differential diagnosis of patients with unexplained gastrointestinal symptoms, especially when other common causes have been ruled out 6, 2