Affect of Proton Pump Inhibitors on Secretin Stimulation Testing for the diagnosis of Zollinger Ellison Syndrome

National Institute Of Diabetes And Digestive And Kidney Diseases

Investigators

Abstract

Zollinger-Ellison syndrome (ZES) is characterized by gastrinoma-induced hypergastrinemia causing excessive gastric acid secretion. Secretin stimulation tests (SSTs) are required for diagnosis in the majority of patients. Two case reports suggest that proton pump inhibitors (PPIs) cause false SST results. Consequently, PPIs are discontinued to allow hyperchlorhydria to recur, however uncontrolled acidity can cause life-threatening complications in those with underlying undiagnosed ZES. To determine whether PPIs influence the validity of SSTs for diagnosis of ZES. A retrospective chart review was performed. Charts of patients who underwent SSTs were reviewed to determine whether they were performed on or off PPI and the tests accuracy by comparing the result with gold standard tests (diagnostic laboratory testing performed off PPI or surgical pathology consistent with gastrinoma). Sensitivity, specificity, and positive predictive value (PPV) of SST on PPI were calculated and results compared with SST off PPI using non-inferiority analyses. 28 patients corresponding to 29 SSTs were performed on PPI and 70 patients corresponding to 107 SSTs were performed off PPI. The majority were female, white, and had multiple endocrine neoplasia type 1. We found no false positive or false negative SSTs on PPI. Sensitivity, specificity, and PPV of SSTs on PPI were determined to be non-inferior to SSTs off PPI (p 0.05 for all). We concluded from our cohort, SSTs on PPI compared to SSTs off PPI were non-inferior in terms of sensitivity, specificity, and PPV. These results suggest that PPI withdrawal prior to SSTs may not be necessary.