Study Objective: To evaluate criteria of positivity for and usefulness of both the secretin and calcium gastrin-provocative tests in patients with the Zollinger-Ellison syndrome.
Design: Prospective trial in consecutive patients.
Setting: Referrals to a clinical research center.
Patients: Consecutive sample of 80 patients with the Zollinger-Ellison syndrome.
Intervention: Kabi-secretin (2 U/kg body weight) given by intravenous bolus and calcium gluconate (10%) (54 mg/kg · h [5 mg/kg · h of calcium]) given by continuous intravenous infusion for 3 hours. Serum gastrin measured at -15, and -1 minutes before, and 2, 5, 10, 15, 20, and 30 minutes after secretin, or every 30 minutes for 3 hours during the calcium infusion. Serum calcium and serum gastrin were measured simultaneously during the calcium infusion.
Measurements and Main Results: There was no significant difference in the responses of patients with different extents or locations of the tumor, presence or absence of multiple endocrine neoplasia, type-I, or with fasting gastrin less than or greater than 1000 pg/mL. In patients with fasting gastrin of less than 1000 pg/mL, the sensitivity of the secretin test using the criterion of an increase in gastrin of at least 110 pg/mL was 93% (CI, 76% to 99%) and for an increase of 200 pg/mL it was 85% (CI, 66% to 96%), (P > 0.05). With the calcium infusion test, the sensitivity using the criterion of an increase of 395 pg/mL was 43% (CI, 23% to 66%) and for an increase of 50% was 74% (CI, 52% to 90%), (P < 0.01). The calcium infusion test was positive in 33% of patients with a negative secretin test. With the secretin test, 75% of patients had a positive response by 5 minutes, 95% by 10 minutes, 100% by 15 minutes, and 6% only at 2 minutes. With calcium infusion, patients had positive responses at 120 to 180 minutes.
Conclusions: The secretin test is preferred over the calcium test because of its greater sensitivity and simplicity. The recommended criteria are a 200 pg/mL increase for the secretin test and a 395 pg/mL increase for the calcium test. The calcium test should be reserved for patients having a negative secretin test, gastric acid hypersecretion, and a strong clinical suspicion of the Zollinger-Ellison syndrome.