Clinical significance of gastrin radioimmunoassay.

Serum gastrin radioimmunoassay (RIA) is a sensitive and specific method suitable for measurement of circulating concentrations of this peptide hormone, which is a major regulator of gastric acid secretion. When performed under optimal conditions this RIA permits measurement of low and normal serum gastrin levels and changes that occur after physiologic stimulation. Hypergastrinemia may be secondary to atrophy of the acid-secreting gastric mucosa. This form of pypergastrinemia is appropriate and leads to no seriousequences. Hypergastrinemia associated with gastric acid hypersecretion is inappropriate. The major cause is a gastrinsecreting tumor (gastrinoma) that produces the clinical picture of the Aollinger-Ellison syndrome. The differential diagnosis of inappropraite hypergastrinemia includes antral G-cell hyperplasia and ISOLATED RETAINED ANTRUM. Accurate diagnosis of these conditions may be aided by ancillary studies including feeding, secretin, and calcium stimulation tests. Distinction among these conditions is important in planning appropriate surgical tratment.