Use of the Biphasic13C-Sucrose/Glucose Breath Test to Assess Sucrose Maldigestion in Adults with Functional Bowel Disorders

Abstract

Sucrase insufficiency has been observed in children with of functional bowel disorders (FBD) and symptoms of dietary carbohydrate intolerance may be indistinguishable from those of FBD. A two-phase13C-sucrose/13C-glucose breath test (13C-S/GBT) was used to assess sucrase activity because disaccharidase assays are seldom performed in adults. When13C-sucrose is hydrolyzed to liberate monosaccharides, oxidation to13CO2is a proportional indicator of sucrase activity. Subsequently,13C-glucose oxidation rate was determined after a secondary substrate ingestion (superdose) to adjust for individual habitus effects (Phase II).13CO2enrichment recovery ratio from13C-sucrose and secondary13C-glucose loads reflect the individualized sucrase activity [Coefficient of Glucose Oxidation for Sucrose(CGO-S)]. To determine if sucrase insufficiency could be a factor in FBD,13C-S/GBT was validated using subjects with known sucrase gene mutation status by comparing13CO2-breath enrichment with plasma13C-glucose enrichment.13C-S/GBT was used to assess sucrose digestion in FBD patients and asymptomatic controls.13CO2-breath enrichment correlated with the appearance of13C-sucrose-derived glucose in plasma (r2=0.80). Mean, control group CGO-S-enrichment outcomes were 1.01 at 60′, 0.92 at 75′, and 0.96 at mean 60′–75′ with normal CGO-S defined as >0.85 (95% C.I.). In contrast, FBD patients demonstrated lower CGO-S values of 0.77 at 60′, 0.77 at 75′, and 0.76 at mean 60′–75′ (Chi Square: 6.55;p<0.01), which points to sucrose maldigestion as a cause of FBD.