NONINVASIVE C-13-OCTANOIC ACID BREATH TES T FOR MEASUREMENT OF SOLID GASTRIC-EMPTYING - COMPARISON TO SCINTIGRAPHY IN DIABETICS AND REPRODUCIBILITY IN HEALTHY-VOLUNTEERS

The recently developed C-13-octanoic acid breath test allows the measu rement of gastric emptying of,solids. In this prospective study we wan ted to investigate, whether the C-13-octanoic acid breath test using b reath samples every half an hour is suitable in assessing gastric empt ying in comparison to scintigraphy in diabetics. Furthermore, we exami ned the intraindividual reproducibility in healthy volunteers. 20 cons ecutive diabetics with clinical symptoms of gastroparesis received a s olid double-labeled standard test meal. The meal consisted of 1 scramb led egg, labeled with 75 mg C-13-octanoic acid and 0.5 mCi Tc-99m coll oid, 50 g rye bread, 20 g butter, 200 ml orange juice; 280 kcal. Breat h samples were taken at half hour intervals for 4 hours and analyzed f or (CO2)-C-13 by isotope ratio mass spectrometry Using a regression me thod gastric emptying half times (t 1/2) were determined and correlati ons to simultaneous (99mTc)-scintigraphy were calculated. There was a moderate significant correlation of C-13-octanoic acid breath test t 1 /2 and scintigraphic t 1/2 (R = 0.6; p = 0.008). The C-13-octanoic aci d breath test t 1/2 obtained in 20 healthy volunteers measured at two separate days showed a coefficient of variation (VC), that was greater between subjects (VK = 42%) than between two measurements in the same subject (VK = 24%), which reflects a moderate intraindividual reprodu cibility. Taking breath samples every half an hour the C-13-octanoic a cid breath test only reveales a moderate intraindividual reproducibili ty and a moderate correlation to scintigraphy in diabetics. For detail ed assessment of solid gastric emptying in diabetics a C-13-octanoic a cid breath test using shorter breath sampling intervals is recommended .