Comparison of Four Provocative Tests for the Diagnosis of Gastrinoma

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Abstract
To determine the best provocative test for the diagnosis of gastrinoma, 10 normal subjects, 13 patients with known gastrinoma, and 1 patient with presumed gastrinoma were administered 4 regimens: rapid Ca infusion (2 mg Ca2+/kg per min); secretin (2 clinical units (CU)/kg per bolus); long Ca infusion (12 mg Ca2+/kg per 3 h) and a combination test consisting of a rapid Ca infusion followed immediately by secretin. Blood was drawn for serum gastrin levels before and following infusion of the test agents. The administration of rapid Ca followed by secretin provoked the greatest increases in serum gastrin above basal levels in both normals (29%) and patients (362%). Peak gastrin levels in patients were similar following the long Ca infusion (341%) but were less following the rapid Ca infusion alone (124%) and secretin alone (207%). There were no false-positive or false-negative tests with the Ca plus secretin when the criterion for diagnosis was either a 50% increase or a 200 pg/ml increase above the basal gastrin level. The distinct advantages (short test period, low patient morbidity, and relatively great potency) of the Ca plus secretin test make it an attractive alternative to other previously described provocative tests for the diagnosis of gastrinoma.