The predictive accuracy of the postvagotomy insulin test: A new interpretation

Insulin-stimulated gastric secretion alone, without reference to basal secretion, has been examined in 45 male patients with duodenal ulcer in whom no gastric operation had been performed and in 124 patients following vagotomy for duodenal ulcer. Gastric juice was examined in terms not only of conventional indices, observed volume, titratable acidity and acid output, but also Vg, the volume corrected for pyloric loss and duodenal reflux. The range of secretion of the unoperated subjects was established in terms of peak and half-totwo-hour values for all indices. By reference to these ranges, secretion of postvagotomy subjects could be divided into two groups: (a) those with secretion within the preperative range, and (b) those with secretion less than the lower limit of the preoperative range. The best discrimination was given by Vg; those within the preoperative range (peak Vg in excess of 140 ml/hour and Vg half to two hours in excess of 105 ml/hour) had a 50% liability to recurrent ulcer, while those below the preoperative range had a zero liability to recurrent ulcer. Of the conventional indices acid output gave the best discrimination, which was almost as good as Vg. Peak acid output of 8 mmol/hour or acid output one half to two hours of 525 mmol/hour discriminated into two groups, with a 50% or zero liability to recurrent ulcer. Titratable acidity (Hollander's index of secretion), being highly susceptible to reflux, was not an adequate discriminant.