The current study evaluated efficacy of the intravenous
calcium injection test as a new diagnostic approach to clarify the existence of
gastrinoma, which often goes undetected with routine testing. Twenty-six patients with hypergastrinemia were studied. For the
calcium injection test, blood samples were taken from 12 patients with hypergastrinemia (HG), and three healthy volunteers, and one patient with nonfunctioning endocrine
tumor in the pancreas (control). We compared results of the
calcium injection test with those of the
secretin test and the selective arterial
secretagogue injection (SASI) test. The SASI test with
secretin was performed in 24 of 26 patients with hypergastrinemia, including 22 of 24 patients with
Zollinger-Ellison syndrome (ZES). Accuracy in the diagnosis of
tumor localization by the SASI test was 95% (21 of 22) in ZES patients. The
secretin test was negative in 3 of 21 patients with ZES (14%). Either the
secretin test or the SASI test was positive in 22 of 23 patients (96%). The
calcium injection test was administered to 12 patients in the HG group and 4 controls. The HG group showed significantly higher serum
gastrin levels than those of the control group in the
calcium injection test. Eight of 10 ZES patients (80%) had a positive
calcium injection test. We could diagnose
gastrinomas in 100% of ZES patients by either the
calcium injection test or the
secretin test. We have thus confirmed the efficacy of the intravenous
calcium injection test in the diagnosis of
gastrinoma. The
calcium injection test could become an adjunct in the diagnosis of
gastrinoma, which often goes undetected with routine testing.