A Duodenal Gastrinoma in a Patient with Diarrhea and Normal Serum Gastrin Concentrations

Abstract

T HE Zollinger-Ellison syndrome manifests itself in 90 to 95 percent of cases as severe peptic ulcer disease. 1 About half the time, the ulcer disease is associated with diarrhea, and in approximately 10 percent of patients, diarrhea is the only clinical manifestation. 2,3 Basal serum gastrin concentrations are usually elevated in patients with this syndrome. 4 Normal basal serum gastrin values with abnormal results of secretin tests have been reported, however, in a few patients. [5][6][7] We describe a patient with a duodenal gastrinoma, a two-year history of diarrhea, and no peptic ulcer disease. The patient had persistently normal serum gastrin concentrations, but abnormal results of a secretin test and increased serum concentrations of the total progastrin product. C ASE R EPORTA 61-year-old man was admitted to the hospital in February 1993 with a two-year history of diarrhea (8 to 10 watery stools per day) and episodes of epigastric pain, but no weight loss. Before this admission, upper and lower gastrointestinal endoscopy, as well as biopsies and an extensive search for infections and parasitic organisms, had been performed. No abnormalities had been found. Treatment with pancreatin, loperamide, and cimetidine by the referring physician had had no effect on the diarrhea.On admission, the stool weight was 1010 g per day; the stool contained normal amounts of fat (6.7 g per day) and chymotrypsin (17.5 U per gram of stool weight). The concentrations of hemoglobin and of serum creatinine, total bilirubin, alkaline phosphatase, aminotransferases, total protein, calcium, and phosphorus were normal, as were the white-cell count and the results of serum protein electrophoresis. Additional laboratory tests, such as those for serum vitamin B 12 , folic acid, thyroid hormones, thyrotropin, gastrin (on three occasions), vasoactive intestinal peptide, and serotonin and for urinary 5-hydroxyindoleacetic acid, were normal, as were the results of tests for malabsorption, including a Schilling test and breath tests for D -xylose, and H 2 -lactose, H 2 -lactulose, and H 2 -glucose. Transabdominal ultrasonography, computed tomography of the abdomen, radiographic examination of the small intestine, and colonoscopy, including histologic examination of biopsy specimens, were also normal. Endoscopy of the upper gastrointestinal tract showed prominent duodenal mucosal folds. Histologic examination of duodenal-biopsy specimens showed shortening of the villi, with moderate infiltration by inflammatory cells. Celiac disease was suspected, and the patient began to follow a gluten-free diet.The patient was sent home in March 1993 and readmitted in October 1993. Despite a gluten-free diet, diarrhea and histologic abnormalities on subsequent duodenal biopsies persisted. Parenteral nutri-tion was started. Nevertheless, the stool weight was 1070 g per day, and the fat and chymotrypsin content was again found to be normal, indicating secretory diarrhea. Basal serum gastrin concentrations were normal on three occasions (20, 32, and 46 pg pe...

Neuroendocrine Tumors of the Gastroenteropancreatic System: I. Diagnostic Advances

“…An abnormal secretin test with an increase in the serum gastrin level of more than 200 pg/ml with 2 U/kg of secretin administered intravenously confirms the diagnosis [25]. In the rare patient with secretory diarrhea and suspected gastrinoma, pathologically high gastrin levels may only be detected in response to secretin [26], In VIPoma patients increased levels of serum VIP (greater than 250 pg/ml) and in glucagonoma patients elevated glucagon levels (higher than 500 pg/ml) are observed. In the rare patients with somatostatinoma, GRFoma, ACTHoma, neurotensinoma or PTHrPoma the respective hormonal parameters, i.e.…”

The Ultimate Biochemical Diagnosis of Neuroendocrine Gastro-Enteropancreatic Tumours

“…An abnormal secretin test with an in crease in the serum gastrin level >200 pg/ml with 2 U/kg of secretin administered intravenously confirms the diag nosis [3]. Normal basal serum gastrin values but patholog ical secretin test results have been reported, however, in a few gastrinoma patients [4] high gastrin levels may only be detected in response to secretin and by increased levels of the total progastrin product [5]. In VIPoma patients, increased levels of serum vasoactive-intestinal peptide (>250 pg/ml) are ob served.…”

Pitfalls in Diagnostic Gastrin Measurements

“…A few gastrinomas, however, may process progastrin so poorly that the concentrations of bioactive amidated gastrins in plasma periodically fluctuate into the reference interval [104 pg/mL (Ͻ50 pmol/L)] while the concentrations of precursors are increased (27,38 ). For these patients, we have designed a processing-independent analysis (39,40 ).…”

“…In other words, 1 peptide fragment is measured stoichiometrically per translated propeptide molecule. Processing-independent assays have been useful as second-line assays for a few gastrinomas with truly normal or only slightly increased plasma concentrations of amidated gastrins (27,38 ). The ability to diagnose selected gastrinomas at an early stage of the disease via processing-independent analysis is therefore valuable.…”