Serum gastrin level is increased by chronic hypercalcemia of parathyroid or nonparathyroid origin

In patients with hypercalcemia with abdominal symptoms, gastrin concentration is often measured to exclude the Zollinger-Ellison syndrome. We found that interpretation of such measurements is clouded by a contradictory literature. We therefore measured serum gastrin concentrations in 78 patients with primary hyperparathyroidism, 36 with nonparathyroid hypercalcemia, 13 with hypocalcemia, and 33 normocalcemic controls. Gastrin values above normal occurred in 22% of those with primary hyperparathyroidism and 28% of those with nonparathyroid hypercalcemia. Values above 250 pg/mL occurred only in those with hypochlorhydria or multiple endocrine neoplasia, type 1 (MEN 1). After parathyroidectomy, gastrin levels fell significantly, but elevated values tended to recur in those with MEN 1 if hypercalcemia recurred. Thus, chronic hypercalcemia of either parathyroid or nonparathyroid origin may elevate serum gastrin concentrations, but marked elevations suggest either achlorhydria or MEN 1.