Comparison of Four Provocative Tests for the Diagnosis of Gastrinoma

Abstract

In an attempt to determine the best provocative test for the diagnosis of gastrinoma, ten normal subjects, 13 patients with known gastrinoma, and one patient with presumed gastrinoma were administered four regimens: (1) rapid calcium infusion (2 mg Ca++/kg/min), (2) secretin (2 clinical units (CU)/kg/bolus), (3) long calcium infusion (12 mg Ca++/kg/3 h) and (4) a combination test consisting of a rapid calcium infusion followed immediately by secretin. Blood was drawn for serum gastrin levels before and following infusion of the test agents. The administration of rapid calcium 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 calcium infusion (341%) but were less following the rapid calcium infusion alone (124%) and secretin alone (207%). There were no false-positive or false-negative tests with the calcium 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 calcium plus secretin test make it an attractive alternative to other previously described provocative tests for the diagnosis of gastrinoma.

Calcium Reverses Octreotide Inhibition of Insulin and Glucagon Levels in Patients with Insulinoma and Glucagonoma

“…These peptide responses can be regulated by a variety of endogenous and pharmacological agents [1][2][3][4]. Octreotide acetate, a somatostatin analogue, is a potent inhibitor of peptide release as well as an inhibitor of tumour growth and angiogenesis [5-7, 9, 22, 23], The mechanism of octreotide action is direct inhibition of peptide secretion via binding of the somatostatin ana logue to one of five membrane-bound receptor subtypes (sst i_5).…”

“…The release of these peptides may be provoked by physiological stimuli such as the ingestion of food or by the administration of a variety of pharmacolog ical stimuli such as calcium, secretin, glucagon or tolbuta mide. The ability of these pharmacological stimuli to pro voke peptide release from functional endocrine tumours forms the basis of clinical provocative testing used to con firm the diagnosis of tumours such as gastrinoma (by cal cium or secretin challenge), insulinoma (by tolbutamide challenge) or VIPomas (by tolbutamide challenge) [1][2][3][4]. Conversely, a patient's response to treatment with cyto toxic agents, surgery or peptide-suppressing agents is K A KG E K ® 1996 s -Karger AG.…”

Chronic Refractory Diarrhoea: A Manifestation of Endocrine Disorders

“…Several provocative tests have been used to differentiate gastrinoma from other causes of hypergastrinaemia such as atrophic gastritis, pernicious anaemia, antral G cell hyperplasia, after vagotomy, renal fail ure, massive small bowel resection, hypercalcaemia and during treatment with histamine Hi antagonist [4,32]. Provocative tests in clude feeding of a standard meal and intrave nous infusion of calcium, secretin and bombe sin [30], The secretin provocative test appears to be superior to other tests [67][68][69][70][71], An increase of plasma gastrin by at least 200 pg/ ml after intravenous injection of secretin has been proved to be the most reliable sign for the presence of gastrinoma [30]. In other con ditions with hypergastrinaemia and in normal subjects secretin lowers the plasma gastrin levels [30,54], As previously mentioned, gas trinoma patients also suffer from gastric acid hypersecretion.…”

Peptide Hormones as Tumor Markers in Neuroendocrine Gastrointestinal Tumors

“…Pure natural GIH secretin, either a standard dose or an individualized dose, is administered as a bolus injection intravenously and serum gastrin measured at 5-min intervals for 30 min. Some authors recommend that calcium should be given immediately before the secretin injection to increase the sensitivity of the test (16). The definition of a positive test might also be discussed.…”

“…Presented at the Meeting on Recent Advances in Diagnosis and Treatment of Neuroendocrine Gut and Pancreatic Tumors held in Kebnekaise, Sweden, June 13- 16,1990.…”