Combined Carbon-13-Glycine/Carbon-14-Octanoic Acid Breath Test to Monitor Gastric Emptying Rates of Liquids and Solids

The aim of the present study was to develop a dual-carbon-labeled breath test for simultaneously measuring gastric emptying rates of liquids and solids with significantly less radiation burden to the patient than the radioscintigraphic technique. A test meal was used in which the liquid phase was labeled with two markers, i.e., 3.7 MBq of 111In-DTPA and 100 mg of 13C-glycine; the solid phase also was dually labeled with 110 MBq of 99mTc-albumin colloid and 74 kBq of 14C-octanoic acid. Simultaneous radioscintigraphic and breath-test measurements were performed in 27 subjects, 10 normal controls and 17 patients with dyspeptic symptoms. Mathematic analysis of the excretion rate of labeled CO2 allowed the definition of four parameters, i.e., the gastric emptying coefficient, the gastric half-emptying time, the peak excretion time and the lag phase. There was a good to excellent correlation between the gastric emptying coefficient and the scintigraphic half-emptying time (r = 0.74 for liquids and r = 0.88 for solids), between the half-emptying time determined by breath test and the scintigraphic half-emptying time (r = 0.91 for liquids and r = 0.92 for solids), between the peak excretion time and the scintigraphic half-emptying time (r = 0.91 for liquids and r = 0.96 for solids) and between the lag phase of solid emptying determined by both techniques (r = 0.89). The dual carbon-labeled breath test is a valid, minimally invasive technique to measure the gastric emptying rate of both liquids and solids.