Background:
In patients with sucrase-isomaltase deficiency (SID), sucrose is poorly metabolized by a specific disaccharidase in the intestinal brush border. Sucrose maldigestion promotes bacterial fermentation which can lead to symptoms of diarrhea, bloating, and abdominal pain. Endoscopic biopsy with disaccharide assay (DA) is considered the gold-standard test for diagnosing SID, although less invasive testing with a carbon-13 (C13) sucrose breath test can also be used to diagnose sucrose maldigestion. Treatment of sucrose maldigestion consists of enzyme replacement therapy with sacrosidase and/or sucrose dietary restriction.

Aim: Analysis from a prospective, US, single-center study assessing the clinical response to enzyme replacement therapy with sacrosidase and a low sucrose diet in patients with low sucrase activity detected by DA or C13.

Methods:
Adult (>18 years) patients with chronic diarrhea were recruited and tested for sucrase maldigestion. Exclusion criteria included pregnancy, lactation, severe GI co-morbidities, and previous GI surgeries (excluding cholecystectomy or appendectomy). Eligible patients completed EGD with small intestinal biopsies distal to the ampulla of Vater that underwent DA (Joli Labs) to measure sucrase activity (normal sucrase activity: >28.0 mM/min/g) as well as C13 sucrose breath testing (Metabolic Solutions). Patients diagnosed with sucrase maldigestion based on abnormal DA and/or C13 were treated with enzyme replacement with sacrosidase and a low sucrose diet.

Results:
66 patients with chronic diarrhea underwent EGD with DA, C13 sucrose breath testing, or both. 23 (34.8%) were diagnosed with sucrase deficiency based on at least one abnormal diagnostic test and 20 patients were treated with sacrosidase and a low sucrose diet. 3 patients were lost to follow-up. 50% of patients diagnosed with sucrase maldigestion responded to therapy (40% of patients with positive C13, 80% with positive DA). In 5% of patients, symptoms resolved spontaneously. The distribution of test results are presented in Table 1.

Conclusion:
In the evaluation of patients with chronic diarrhea, assessing for sucrose maldigestion can yield a diagnosis and provide patients with pathophysiologic-directed treatment options including sucrase replacement therapy and/or dietary sucrose restriction. Among patients diagnosed with sucrase maldigestion, 50% responded to therapy. Patients diagnosed based on abnormal DA were more likely to respond to treatment than those diagnosed based on abnormal C13, supporting DA as the preferred test for sucrase maldigestion. This study highlights the yield of testing for and treating sucrase maldigestion in patients with chronic diarrhea and IBS-D symptoms.

Table 1: Symptom improvement with sacrosidase +/- low sucrose diet in patients with low sucrase activity on DA or C13 sucrose breath test

Asad Rehman

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