GAST and cholesteryl ester measurement: Thus, the hypergastrinemia associated with CE and antisecretory therapy appears unlikely to compromise a diagnosis of gastrinoma in dogs, which differs from studies in people where a substantial overlap among those patient groups has been seen [41] and treatment with a PPI or H2A was associated with plasma gastrin concentrations being more than 20-fold higher than in acid-suppressant-naïve patients.