P1569 - Hidden Malabsorptive Syndrome: Sucrase-Isomaltase Deficiency Finally Unveiled in Adulthood

Haider S. Khalil, MD, Kaely Bade, MD
Parkview Health, Fort Wayne, IN

Introduction: Sucrase-Isomaltase Deficiency (SID) is a rare congenital disorder which often presents as chronic diarrhea in children. SID prevents the digestion of sucrose and isomaltose, leading to malabsorption. The unabsorbed carbohydrates provide a substrate for bacterial fermentation, leading to abdominal discomfort, bloating and flatulence.

Case Description/Methods: A 42-year-old male with a history of GERD presents to clinic with a 15-year history of multiple GI symptoms including heartburn, bloating, belching and a non-specific pain sensation throughout his GI tract. He had seen multiple primary care and GI speciality clinics throughout the years. Initially believed to have GERD, he was trialed on multiple courses of different proton pump inhibitors (PPIs) and H2 blockers without improvement. He experienced 30-pound unintentional weight loss over a year, prompting further evaluation with multiple EGDs and colonoscopies. Stomach biopsies showed chronic inflammation, but were otherwise negative for metaplasia, malignancy, histologic abnormalities or H. pylori. EGD showed LA grade A reflux esophagitis and flattened duodenal mucosa, but were otherwise unremarkable. With a lack of clinical improvement, further investigations including MRI enterography and gastric emptying study were performed and negative. For multiple years, the patient was thought to have Irritable Bowel Syndrome (IBS) and Small intestinal bacterial overgrowth (SIBO). Linaclotide and impramine provided very mild relief over the years. His lab work and infectious workup were always negative aside from a positive lactoferrin. He had mild symptomatic improvement when trialed on the FODMAP diet over the past year, but no resolution. Eventually, a C-sucrose breath test was performed and positive. This prompted a duodenal biopsy confirming SID and the patient was started on sacrosidase, resolving his symptoms.

Discussion: Sucrase-isomaltase is an enzyme found on the brush-border membrane of the small intestine. SID causes hydrogen and methane production from fermentation of unabsorbed carbohydrates, leading to malabsorptive symptoms. It is usually diagnosed in infancy, however, can be undiagnosed or masquerade as an IBS misdiagnosis if symptoms are not appreciated by parents or investigated. This case aims to raise awareness for clinicians to not anchor on the most common causes of these GI symptoms, especially if there has been repeated negative work-up and to investigate enzyme deficiencies as a cause of malabsorptive symptoms.


Disclosures:


Haider S. Khalil, MD, Kaely Bade, MD. P1569 - Hidden Malabsorptive Syndrome: Sucrase-Isomaltase Deficiency Finally Unveiled in Adulthood, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.