13C-breath tests for sucrose digestion in congenital sucrase isomaltase-deficient and sacrosidase-supplemented patients

BACKGROUND: Congenital sucrase-isomaltase deficiency (CSID) is characterized by absence or deficiency of the mucosal sucrase-isomaltase enzyme. Specific diagnosis requires upper gastrointestinal biopsy with evidence of low to absent sucrase enzyme activity and normal histology. The hydrogen breath test (BT) is useful, but is not specific for confirmation of CSID. We investigated a more specific C-sucrose labeled BT. OBJECTIVES: Determine whether CSID can be detected with the C-sucrose BT without duodenal biopsy sucrase assay, and if the C-sucrose BT can document restoration of sucrose digestion by CSID patients after oral supplementation with sacrosidase (Sucraid). METHODS: Ten CSID patients were diagnosed by low biopsy sucrase activity. Ten controls were children who underwent endoscopy and biopsy because of dyspepsia or chronic diarrhea with normal mucosal enzymes activity and histology. Uniformly labeled C-glucose and C-sucrose loads were orally administered. CO2 breath enrichments were assayed using an infrared spectrophotometer. In CSID patients, the C-sucrose load was repeated adding Sucraid. Sucrose digestion and oxidation were calculated as a mean percent coefficient of glucose oxidation averaged between 30 and 90 minutes. RESULTS: Classification of patients by C-sucrose BT percent coefficient of glucose oxidation agreed with biopsy sucrase activity. The breath test also documented the return to normal of sucrose digestion and oxidation after supplementation of CSID patients with Sucraid. CONCLUSIONS: C-sucrose BT is an accurate and specific noninvasive confirmatory test for CSID and for enzyme replacement management.