Impaired gastric emptying of a solid test meal in patients with Parkinson's disease using 13C-sodium octanoate breath test

Up to now gastric emptying in patients with Parkinson's disease was determined by radioscintigraphy. The 13C-sodium octanoate breath test (OBT) has been established for the non-invasive evaluation of gastric emptying with a solid test meal. The aim of the study was to evaluate the OBT in patients with Parkinson's disease and to investigate the prevalence of delayed gastric emptying for solids in PD and the relationship to clinical staging patterns. Twenty-two healthy subjects and 36 patients with different clinical stages of PD classified using Hoehn and Yahr (H&Y) and Unified Parkinson's Disease Rating Scale (UPDRS) were studied. Each fasting control and patient received a solid test meal (241 kcal) labelled with 100 mg of 13C-sodium octanoate. Breath samples were obtained before substrate administration and then in 15-min intervals over 4 h. The 13CO2/12CO2 ratio was determined in each breath sample as delta over baseline. Time to peak (tpeak), gastric half emptying time (t1/2b), lag phase (tlagb) and gastric emptying coefficient (GEC) were calculated. Significant differences in tpeak, t1/2b, tlagb and GEC were found between patients and healthy volunteers (p < 0.0001), with a 60% delay in gastric half emptying time in the patient group. Gastric half emptying time was different between clinical disease groups (H&Y 0-2 versus H&Y 2.5-5, p = 0.001; UPDRS 0-30 versus UPDRS 61-92, p < 0.05). The OBT detects a significant delay in gastric emptying of a solid test meal in patients with PD. Delayed gastric emptying for solids is associated with disease severity.