The relationship between technetium 99m pertechnetate gastric scanning and gastric contents.

In order to elucidate the gastric handling of 99Tcm, we performed scintiscanning under basal and stimulated conditions while simultaneously monitoring gastric outputs of water and sodium, hydrogen and 99Tcm pertechnetate ions in six healthy fasting volunteers. Our results showed that gastric scintiscanning correlated well with gastric luminal 99Tcm activity (r = 0.99). However, clearance of 99Tcm from plasma into the gastric lumen showed only a poor correlation with hydrogen ion output (r = 0.68) and no correlation with sodium output. Explanation of these results on a cellular basis can be achieved by assuming a two-component mechanism for 99Tcm secretion, with both the parietal cells (H+ ion secretory) and non-parietal cells (Na+ ion secretory) contributing to 99Tcm gastric output. The relative contribution of each cell type to total 99Tcm secretion is dependent on the degree of gastric stimulation, with non-parietal 99Tcm secretion dominating in the basal state and parietal 99Tcm secretion dominating in the stimulated state. It is concluded therefore, that gastric scintiscanning with 99Tcm pertechnetate should stand only as an empirical test of gastric function and not as a means of measuring acid output.