An automated method for the determination of intestinal disaccharidase and glucoamylase activities

Genetic and acquired sucrase-isomaltase deficiency: A clinical review

Genetic sucrase-isomaltase deficiency (GSID) is an inherited deficiency in the ability to digest sucrose and potentially starch due to mutations in the sucrase-isomaltase (SI) gene. Congenital sucrase-isomaltase deficiency is historically considered to be a rare condition affecting infants with chronic diarrhea as exposure to dietary sucrose begins. Growing evidence suggests that individuals with SI variants may present later in life, with symptoms overlapping with those of irritable bowel syndrome. The presence of SI genetic variants may, either alone or in combination, affect enzyme activity and lead to symptoms of different severity. As such, a more appropriate term for this inherited condition is GSID, with a recognition of a spectrum of severity and onset of presentation. Currently, disaccharidase assay on duodenal mucosal tissue homogenates is the gold standard in diagnosing SI deficiency. A deficiency in the SI enzyme can be present at birth (genetic) or acquired later, often in association with damage to the enteric brush-border membrane. Other noninvasive diagnostic alternatives such as sucrose breath tests may be useful but require further validation. Management of GSID is based on sucrose and potentially starch restriction tailored to the individual patients' tolerance and symptoms. As this approach may be challenging, additional treatment with commercially available sacrosidase is available. However, some patients may require continued starch restriction. Further research is needed to clarify the true prevalence of SI deficiency, the pathobiology of single SI heterozygous mutations, and to define optimal diagnostic and treatment algorithms in the pediatric population.

Sucrase-Isomaltase Deficiency as a Potential Masquerader in Irritable Bowel Syndrome

BACKGROUND

Patients with irritable bowel syndrome (IBS) frequently have meal-related symptoms and can recognize specific trigger foods. Lactose intolerance is a well-established carbohydrate malabsorption syndrome that causes symptoms similar to IBS such as bloating, abdominal pain, and diarrhea. However, the prevalence of sucrase-isomaltase deficiency (SID) in this population is poorly defined. SID is a condition in which sucrase-isomaltase, an enzyme produced by brush border of small intestine to metabolize sucrose, is deficient. Just like lactase deficiency, SID causes symptoms of maldigestion syndromes including abdominal pain, bloating, gas, and diarrhea. In this study, we aim to determine the prevalence of SID in patients with presumed IBS-D/M and characterize its clinical presentation.

METHODS

Patients with a presumed diagnosis of IBS-D/M based on symptoms of abdominal pain, diarrhea, and/or bloating who underwent esophagogastroduodenoscopy with duodenal biopsies and testing for disaccharidase deficiency were included. Patients with a history of inflammatory bowel disease, gastrointestinal malignancy, or celiac disease were excluded. Odds ratio was calculated for abdominal pain, diarrhea, and bloating in patients with versus without SID.

RESULTS

A total of 31 patients with clinical suspicion for IBS-D/M were included with a median age of 46 years (IQR 30.5-60) and with 61% females. SID was present in 35% of patients. Among patients with SID, 63.6% had diarrhea, 45.4% had abdominal pain, and 36.4% had bloating. Patients with SID were less likely than controls to have abdominal pain (OR 0.16, 95% CI 0.03-0.81, p = 0.04) although no difference in diarrhea or bloating was found. Only two patients with SID underwent sucrose breath testing of which only one had a positive result. However, this patient also had a positive glucose breath test and may have had small intestinal bacterial overgrowth as a confounder.

CONCLUSION

SID was found in 35% of patients with presumed IBS-D/M and should be considered in the differential diagnosis of patients presenting with abdominal pain, diarrhea, or bloating. Further studies should better characterize the clinical features of SID and investigate the effects of dietary modification in this group of patients.

Duodenal Disaccharidase Activities During and After Weaning off Parenteral Nutrition in Pediatric Intestinal Failure

OBJECTIVES

Data on factors affecting absorptive function in children with intestinal failure (IF) are sparse. We evaluated duodenal disaccharidase activities and inflammation in relation to parenteral nutrition (PN) and intestinal resection in pediatric onset IF.

METHODS

Disaccharidase (maltase, sucrase, and lactase) activities and histologic inflammation were evaluated from duodenal biopsies in 58 patients during PN (n = 23) or full enteral nutrition (n = 40) and in 43 matched controls. The first and the last postresection biopsies were analyzed separately after 4.3 (1.2-9.7) years and 6.5 (2.3-12.4) years, respectively.

RESULTS

During PN, maltase and sucrase activities were 1.6-fold lower and mucosal inflammation more frequent (22% vs 3%) when compared to matched controls (P < 0.05 for both). In patients on full enteral nutrition, activities of maltase and sucrase were significantly higher than that in patients receiving PN and comparable to those of matched controls. Postresection time correlated positively (r = 0.448 and r = 0.369) and percentage length of the remaining small intestine inversely (r = -0.337 and r = -0.407) with maltase and sucrase activity in patients on full enteral nutrition (P < 0.05 for all), whereas proportional length of remaining colon correlated positively with maltase and lactase activity (r = 0.424-0.544, P < 0.05) in patients receiving PN.

CONCLUSIONS

In children with IF, PN dependency associated with decreased duodenal maltase and sucrase activities and mucosal inflammation, which may disturb intestinal absorptive function. Localization and extent of intestinal resection and post-resection time correlated with duodenal disaccharidase activities.