The fasting concentrations of total
gastrin and
gastrin-17 (G-17) were similar in healthy volunteers and in asymptomatic patients with
gastric ulcers or
duodenal ulcers. However, the fasting serum concentration of gastrin-34 (G-34) was higher in patients with
gastric ulcers than in normal subjects, in whom it was higher than in patients with
duodenal ulcers. In response to food, the increases in G-17, G-34, and total
gastrin were greater in
ulcer patients than in healthy subjects.
Cimetidine administration was associated with further increases in G-17, G-34, and total
gastrin in normal subjects and
gastric ulcer patients after meals. The ratio
G-17/G-34 was similar in placebo-treated normal subjects and placebo-treated patients with gastric or
duodenal ulcers.
Cimetidine produced an increase in
G-17/G-34 in placebo-treated normal subjects and placebo-treated patients with gastric or
duodenal ulcers, but the ratio
G-17/G-34 was greater in patients with
gastric ulcers than in normal subjects. These results indicate that: differences in serum
gastrin concentrations between patient groups, treatment regimens, and time of day are better detected by measuring G-17 and G-34 rather than total
gastrin; there are differences in fasting and food-stimulated
gastrin concentrations between normal subjects and patients with gastric or
duodenal ulcers; the fasting concentration of G-34 is higher than G-17 in normal subjects and patients with
gastric ulcers but not in patients with
duodenal ulcers; food increases G-17 in all subjects but G-34 only in subjects with
gastric ulcers;
cimetidine increases the fasting concentration of total
gastrin in normal subjects and patients with
gastric ulcers and increases G-17 and G-34 in normal subjects;
cimetidine increases the ratio
G-17/G-34 in normal subjects and patients with
gastric ulcers, but decreases
G-17/G-34 in patients with
duodenal ulcers. It is proposed: that measurements of total
gastrin concentration should be replaced by measurements of G-17 and G-34 and that such measurements of G-17 and G-34 indicate differences in serum
gastrin concentrations between normal subjects and those with
peptic ulcers and between those with gastric versus
duodenal ulcers. The role of altered
gastrin metabolism in the pathogenesis of
ulcers needs to be established.