Although scintigraphy, a non-invasive procedure, is usually considered to be the reference technique for measuring gastric emptying in humans,1 several drawbacks limit its application in routine practice. Expensive equipment is required and access to a nuclear medicine department, and the use of radioactive isotopes (generally ^99mTc and ¹¹¹In) can produce low but significant irradiation.2 It is difficult to repeat the technique at frequent intervals or to use it with certain patients such as children or pregnant women. However, these disadvantages are not involved when stable isotopes are used. In 1993, Ghoos et al 3 were the first to report a novel technique based on the use of ¹³C octanoic acid, a medium chain fatty acid which is rapidly absorbed in the duodenum and metabolised in the liver.4 ,5 Following oxidation, the resulting¹³CO₂ is excreted into breath at a level which can easily be detected and measured by isotope ratio mass spectrometry.6 After validation of the ¹³C octanoic breath test in healthy subjects, the same authors developed several applications, including pathophysiological and pharmacological studies.7-12 However, the test has not been validated on a large scale by other groups. Initial work of Choi et alwas less promising,13 but a recent report from the same team did find a statistically significant correlation between scintigraphy and breath test.14

The purpose of the international multicentric study reported in abstract 1 was twofold: firstly, to validate the accuracy and reproducibility of the test on a large scale by reference to gastric scintigraphy, regarded as the gold standard; and secondly, to define the reference values for clinical, pharmacological, and pathophysiological studies. To facilitate comparison with the Ghoos study, the mathematical model developed by their group was used,3 ,15 but …