Zollinger-Ellison syndrome revisited: diagnosis, biologic markers, associated inherited disorders, and acid hypersecretion

Early detection of multiple endocrine neoplasia type 1: A case report

BACKGROUND

Multiple endocrine neoplasias (MENs) are a group of hereditary diseases involving multiple endocrine glands, and their prevalence is low. MEN type 1 (MEN1) has diverse clinical manifestations, mainly involving the parathyroid glands, gastrointestinal tract, pancreas and pituitary gland, making it easy to miss the clinical diagnosis.

CASE SUMMARY

We present the case of a patient in whom MEN1 was detected early. A middle-aged male with recurrent abdominal pain and diarrhea was admitted to the hospital. Blood tests at admission revealed hypercalcemia and hypophosphatemia, and emission computed tomography of the parathyroid glands revealed a hyperfunctioning parathyroid lesion. Gastroscopy findings suggested a duodenal bulge and ulceration. Ultrasound endoscopy revealed a hypoechoic lesion in the duodenal bulb. Further blood tests revealed elevated levels of serum gastrin. Surgery was performed, and pathological analysis of the surgical specimens revealed a parathyroid adenoma after parathyroidectomy and a neuroendocrine tumor after duodenal bulbectomy. The time from onset to the definitive diagnosis of MEN1 was only approximately 1 year.

CONCLUSION

For patients who present with gastrointestinal symptoms accompanied by hypercalcemia and hypophosphatemia, clinicians need to be alert to the possibility of MEN1.

Contemporary Approaches to the Surgical Management of Pancreatic Neuroendocrine Tumors

The incidence of pancreatic neuroendocrine tumors (PNETs) is on the rise primarily due to the increasing use of cross-sectional imaging. Most of these incidentally detected lesions are non-functional PNETs with a small proportion of lesions being hormone-secreting, functional neoplasms. With recent advances in surgical approaches and systemic therapies, the management of PNETs have undergone a paradigm shift towards a more individualized approach. In this manuscript, we review the histologic classification and diagnostic approaches to both functional and non-functional PNETs. Additionally, we detail multidisciplinary approaches and surgical considerations tailored to the tumor's biology, location, and functionality based on recent evidence. We also discuss the complexities of metastatic disease, exploring liver-directed therapies and the evolving landscape of minimally invasive surgical techniques.

Closed-Loop Gastric Outlet Obstruction Secondary to Duodenal Ulcer in a Patient With Esophageal Stricture

Closed-loop gastric outlet obstruction (GOO) is a rare complication that results from a mechanical obstruction in the pylorus or duodenum. In the early 1990s, the common cause of GOO was peptic ulcer disease, accounting for 5% to 10% of hospital admissions. Peptic ulcer disease is the disruption of the mucosal integrity in the stomach and duodenum and can be categorized into gastric ulcers and duodenal ulcers. With the treatment for Helicobacter  pylori and the increased use of proton pump inhibitors (PPI), GOO now occurs in fewer than 5% of patients with duodenal ulcer disease and even less in those with gastric ulcer disease. Although the morbidity of duodenal ulcers has been declining in recent years, the incidence of post-bulbar duodenal ulcer (PBDU) remains at a constant 9.33%, primarily due to diagnostic and therapeutic difficulties. Additionally, fewer than 5% of obstructing duodenal ulcers are caused by PBDU, and even fewer are located in the second or third portions of the duodenum. Ulcers located in the distal part of the duodenum raise concern for syndromes associated with hypersecretion of acid, including Zollinger-Ellison syndrome (ZES). The ZES is rare, accounting only for 0.1% of all duodenal ulcers. Here, we present a case where a patient with esophageal stricture developed a rare case of closed-loop GOO secondary to a duodenal ulcer. The patient, initially treated for esophageal perforation, developed an esophageal stricture. The patient was being worked up for ZES and multiple endocrine neoplasia link type 1 (MEN1) syndrome due to his concerning laboratory findings and rare clinical presentation.

Gastrinoma and Zollinger Ellison syndrome: A roadmap for the management between new and old therapies

Zollinger-Ellison syndrome (ZES) associated with pancreatic or duodenal gastrinoma is characterized by gastric acid hypersecretion, which typically leads to gastroesophageal reflux disease, recurrent peptic ulcers, and chronic diarrhea. As symptoms of ZES are nonspecific and overlap with other gastrointestinal disorders, the diagnosis is often delayed with an average time between the onset of symptoms and final diagnosis longer than 5 years. The critical step for the diagnosis of ZES is represented by the initial clinical suspicion. Hypergastrinemia is the hallmark of ZES; however, hypergastrinemia might recognize several causes, which should be ruled out in order to make a final diagnosis. Gastrin levels > 1000 pg/mL and a gastric pH below 2 are considered to be diagnostic for gastrinoma; some specific tests, including esophageal pH-recording and secretin test, might be useful in selected cases, although they are not widely available. Endoscopic ultrasound is very useful for the diagnosis and the local staging of the primary tumor in patients with ZES, particularly in the setting of multiple endocrine neoplasia type 1. Some controversies about the management of these tumors also exist. For the localized stage, the combination of proton pump inhibitory therapy, which usually resolves symptoms, and surgery, whenever feasible, with curative intent represents the hallmark of gastrinoma treatment. The high expression of somatostatin receptors in gastrinomas makes them highly responsive to somatostatin analogs, supporting their use as anti-proliferative agents in patients not amenable to surgical cure. Other medical options for advanced disease are super-imposable to other neuroendocrine neoplasms, and studies specifically focused on gastrinomas only are scant and often limited to case reports or small retrospective series. The multidisciplinary approach remains the cornerstone for the proper management of this composite disease. Herein, we reviewed available literature about gastrinoma-associated ZES with a specific focus on differential diagnosis, providing potential diagnostic and therapeutic algorithms.

Multiple endocrine neoplasia type 1 (MEN-1) and neuroendocrine neoplasms (NENs)

Neuroendocrine neoplasms (NENs) are relatively rare neoplasms with 6.4-times increasing age-adjusted annual incidence during the last four decades. NENs arise from neuroendocrine cells, which release hormones in response to neuronal stimuli and they are distributed into organs and tissues. The presentation and biological behaviour of the NENs are highly heterogeneous, depending on the organ. The increased incidence is mainly due to increased awareness and improved detection methods both in the majority of sporadic NENs (non-inherited), but also the inherited groups of neoplasms appearing in at least ten genetic syndromes. The most important one is multiple endocrine neoplasia type 1 (MEN-1), caused by mutations in the tumour suppressor gene MEN1. MEN-1 has been associated with different tumour manifestations of NENs e.g. pancreas, gastrointestinal tract, lungs, thymus and pituitary. Pancreatic NENs tend to be less aggressive when arising in the setting of MEN-1 compared to sporadic pancreatic NENs. There have been very important improvements over the past years in both genotyping, genetic counselling and family screening, introduction and validation of various relevant biomarkers, as well as newer imaging modalities. Alongside this development, both medical, surgical and radionuclide treatments have also advanced and improved morbidity, quality of life and mortality in many of these patients. Despite this progress, there is still space for improving insight into the genetic and epigenetic factors in relation to the biological mechanisms determining NENs as part of MEN-1. This review gives a comprehensive update of current evidence for co-occurrence, diagnosis and treatment of MEN-1 and neuroendocrine neoplasms and highlight the important progress now finding its way to international guidelines in order to improve the global management of these patients.

One-Year Postoperative Mortality in MEN1 Patients Operated on Gastric and Duodenopancreatic Neuroendocrine Tumors: An AFCE and GTE Cohort Study

IMPORTANCE

In MEN1 patients with gastric and duodenopancreatic neuroendocrine tumors (GPD-NET), surgery aims to control secretions or to prevent metastatic spread, but after GPD-NET resection, postoperative mortality may be related to the surgery itself or to other associated MEN1 lesions with their own uncontrolled secretions or metastatic behavior.

OBJECTIVE

To analyze the causes of death within 1 year following a GPD-NET resection in MEN1 patients.

DESIGN

An observational study collecting data from the Groupe d'étude des Tumeurs Endocrines (GTE) database. The analysis considered the time between surgery and death (early deaths [<1 month after surgery] versus delayed deaths [beyond 1 month after surgery]) and the period (before 1990 vs after 1990). Causes of death were classified as related to GDP surgery, related to surgery for other MEN1 lesions or not related to MEN1 causes.

SETTING

GTE database which includes 1220 MEN1 patients and 441 GPD-NET resections.

PARTICIPANTS

Four hundred and forty-one GPD-NET resections.

MAIN OUTCOME MEASURES

The primary end point was postoperative mortality within 1 year after surgery.

RESULTS

Twenty-four patients met the inclusion criteria (2%). Median age at death was 50.5 years. Sixteen deaths occurred in the 30-day postoperative period (76%). Among the 8 delayed deaths, 3 occurred as a result of medical complications between 30 and 90 postoperative days. After 1990, mean age at death increased from 48 to 58 years (p = 0.09), deaths related to uncontrolled acid secretion disappeared (p < 0.001) and deaths related to associated MEN1 lesions increased from 8 to 54% (p = 0.16).

CONCLUSION

Surgery and uncontrolled secretions remain the two main causes of death in MEN1 patients operated for a GPD-NET tumor. Improving the prognosis of these patients requires a strict evaluation of the secretory syndrome and MEN1 aggressiveness before GDP surgery.

Gamma Emitters in Pancreatic Endocrine Tumors Imaging in the PET Era: Is there a Clinical Space for 99mTc-peptides?

Background:

Pancreatic Neuroendocrine Tumors (PNETs) are rare neoplasms, sporadic or familial, even being part of a syndrome. Their diagnosis is based on symptoms, hormonal disorders or may be fortuitous. The role of Nuclear Medicine is important, mainly because of the possibility of a theranostic strategy. This approach is allowed by the availability of biochemical agents, which may be labeled with radionuclides suitable for diagnostic or therapeutic purposes, showing almost identical pharmacokinetics. The major role for radiopharmaceuticals is connected with radiolabeled Somatostatin Analogues (SSA), since somatostatin receptors are highly expressed on some of the neoplastic cell types.

Discussion:

Nowadays, in the category of radiolabeled SSA, although 111In-pentetreotide, firstly commercially proposed, is still used, the best choice for diagnosis is related to the so called DOTAPET radiotracers labeled with 68-Gallium (Ga), such as 68Ga-DOTATATE, 68Ga-DOTANOC, and 68Ga-DOTATOC. More recently, labeling with 64-Copper (Cu) (64Cu-DOTATATE) has also been proposed. In this review, we discuss the clinical interest of a SAA (Tektrotyd©) radiolabeled with 99mTc, a gamma emitter with better characteristics, with respect to 111Indium, radiolabeling Octreoscan ©. By comparing both pharmacokinetics and pharmacodynamics of Octreoscan©, Tektrotyd© and PET DOTA-peptides, on the basis of literature data and of our own experience, we tried to highlight these topics to stimulate further studies, individuating actual clinical indications for all of these radiotracers.

Conclusion:

In our opinion, Tektrotyd© could already find its applicative dimension in the daily practice of NETs, either pancreatic or not, at least in centers without a PET/CT or a 68Ga generator. Because of wider availability, a lower cost, and a longer decay, compared with respect to peptides labeled with 68Ga, it could be also proposed, in a theranostic context, for a dosimetry evaluation of patients undergoing Peptide Receptor Radionuclide Therapy (PRRT), and for non-oncologic indications of radiolabelled SSA. In this direction, and for a more rigorous cost/effective evaluation, more precisely individuating its clinical role, further studies are needed.

The Zollinger-Ellison syndrome: is there a role for somatostatin analogues in the treatment of the gastrinoma?

PURPOSE

Analyze the role of somatostatin analogues (SSAs) in the treatment of sporadic and MEN1-related gastrinomas, trying to define whether recent trials have changed the landscape of gastrinoma therapy.

METHODS

We evaluate the rationale of SSA use in the treatment of gastrinomas, summarize the current literature concerning the effect of SSAs on the control of Zollinger-Ellison syndrome (ZES) and gastrinomas tumor progression and discuss their role in the most recent guidelines.

RESULTS

The medical treatment of gastrinoma and related ZES is aimed at controlling acid hypersecretion and tumor progression, in inoperable patients. The use of proton pump inhibitors (PPIs) to control the syndrome is a cornerstone in the ZES therapy. SSAs are not usually indicated for antisecretory purpose, because PPIs are considered the treatment of choice, due to their long lasting high efficacy and oral availability. The antiproliferative effect of SSAs has been established by two placebo-controlled trials that have clearly demonstrated a significant increase in progression free survival in patients affected by non-functioning well-differentiated advanced neuroendocrine tumors (NETs). The recent ENETS guidelines recommend the use of SSAs in advanced well differentiated NETs as antiproliferative agents.

CONCLUSIONS

The high sstr-expression in gastrinomas make them highly responsive to SSAs and support the use of such drugs to counteract the tumour growth in patients not amenable to surgical cure. Unfortunately, limited data, mainly case reports or small series, support the use of SSAs in advanced gastrinomas, therefore, it is difficult to quantify their ability to control tumour growth and disease progression.

Catching the Zebra: Clinical Pearls and Pitfalls for the Successful Diagnosis of Zollinger-Ellison Syndrome

Zollinger-Ellison syndrome (ZES) results from an ectopic gastrin-secreting tumor leading to peptic ulcer disease, reflux, and chronic diarrhea. While early recognition portends an excellent prognosis with >80% survival at 15 years, symptoms are often nonspecific making the diagnosis difficult to establish. Diagnosis involves a series of tests, including fasting gastrin, gastric pH, chromogranin A, and secretin stimulation. Performing these tests in the correct sequence and at the proper time is essential to avoid inaccurate results. Tumor localization is equally nuanced. Although providers have classically used ¹¹¹indium-radiolabeled octreotide with somatostatin receptor scintigraphy to evaluate tumor size and metastases, recent studies have shown superior results with newer imaging modalities. In particular, ⁶⁸gallium (⁶⁸Ga)-labeled somatostatin radiotracers (i.e., ⁶⁸Ga-DOTATOC, ⁶⁸Ga-DOTANOC and ⁶⁸Ga-DOTATATE) used with positron emission tomography/computed tomography can provide excellent results. Endoscopic ultrasound is another useful modality, particularly in patients with ZES in the setting of multiple endocrine neoplasia type 1. This review aims to provide clinicians with an overview of ZES with a focus on both clinical presentation and the proper utilization of the various biochemical and imaging tests available.

A Perplexing Case of Abdominal Pain That Led to the Diagnosis of Zollinger-Ellison Syndrome

Zollinger-Ellison syndrome (ZES) is a rare clinical disorder, characterized by hypersecretion of gastric acid and multiple ulcers distal to the duodenal bulb. This occurs via the release of gastrin by neuroendocrine tumors known as gastrinomas. Patients with ZES present with nonspecific GI symptoms, which often leads to a delay in diagnosis. Our patient is a 55-year-old female with chronic abdominal pain, nausea, and diarrhea. She underwent EGD, EUS, MRCP, CT scans, and cholecystectomy, which did not reveal the cause of her symptoms. Repeat EGD showed a cratered ulcer in the second portion of the duodenum, suspicious for ZES. Serum gastrin was initially only moderately elevated while on PPI therapy, but chromogranin A was also elevated. Repeat gastrin level after stopping PPI therapy was 1639 pg/mL. Somatostatin receptor scintigraphy was obtained, which showed two small lesions in the gastrinoma triangle. She subsequently underwent a Whipple pancreaticoduodenectomy and pathology was positive for four microscopic foci of a neuroendocrine tumor. She reported improvement in her symptoms after surgery. This case highlights the need for increased awareness of ZES in patients with unexplained GI complaints and emphasizes the use of multiple modalities in the diagnosis of ZES.

Minimally Invasive Techniques for Resection of Pancreatic Neuroendocrine Tumors

Surgical resection remains the treatment of choice for primary pancreatic neuroendocrine tumors (PNETs), because it is associated with increased survival. Minimally invasive procedures are a safe modality for the surgical treatment of PNETs. In malignant PNETs, laparoscopy is not associated with a compromise in terms of oncologic resection, and provides the benefits of decreased postoperative pain, better cosmetic results, shorter hospital stay, and a shorter postoperative recovery period. Further prospective, multicenter, randomized trials are required for the analysis of these minimally invasive surgical techniques for the treatment of PNETs and their comparison with traditional open pancreatic surgery.

Metastatic gastrinoma in a pediatric patient with Zollinger-Ellison syndrome

Metastatic neuroendocrine tumors of childhood are extremely rare, and as such present diagnostic and therapeutic challenges. Here, we report a case of gastrinoma with extensive hepatic metastases in a pediatric patient with Zollinger-Ellison Syndrome who underwent orthotopic liver transplant followed by cytotoxic chemotherapy, somatostatin analog therapy, and immune modulation.

Causes of death and prognostic factors in multiple endocrine neoplasia type 1: a prospective study: comparison of 106 MEN1/Zollinger-Ellison syndrome patients with 1613 literature MEN1 patients with or without pancreatic endocrine tumors

Multiple endocrine neoplasia type 1 (MEN1) is classically characterized by the development of functional or nonfunctional hyperplasia or tumors in endocrine tissues (parathyroid, pancreas, pituitary, adrenal). Because effective treatments have been developed for the hormone excess state, which was a major cause of death in these patients in the past, coupled with the recognition that nonendocrine tumors increasingly develop late in the disease course, the natural history of the disease has changed. An understanding of the current causes of death is important to tailor treatment for these patients and to help identify prognostic factors; however, it is generally lacking.To add to our understanding, we conducted a detailed analysis of the causes of death and prognostic factors from a prospective long-term National Institutes of Health (NIH) study of 106 MEN1 patients with pancreatic endocrine tumors with Zollinger-Ellison syndrome (MEN1/ZES patients) and compared our results to those from the pooled literature data of 227 patients with MEN1 with pancreatic endocrine tumors (MEN1/PET patients) reported in case reports or small series, and to 1386 patients reported in large MEN1 literature series. In the NIH series over a mean follow-up of 24.5 years, 24 (23%) patients died (14 MEN1-related and 10 non-MEN1-related deaths). Comparing the causes of death with the results from the 227 patients in the pooled literature series, we found that no patients died of acute complications due to acid hypersecretion, and 8%-14% died of other hormone excess causes, which is similar to the results in 10 large MEN1 literature series published since 1995. In the 2 series (the NIH and pooled literature series), two-thirds of patients died from an MEN1-related cause and one-third from a non-MEN1-related cause, which agrees with the mean values reported in 10 large MEN1 series in the literature, although in the literature the causes of death varied widely. In the NIH and pooled literature series, the main causes of MEN1-related deaths were due to the malignant nature of the PETs, followed by the malignant nature of thymic carcinoid tumors. These results differ from the results of a number of the literature series, especially those reported before the 1990s. The causes of non-MEN1-related death for the 2 series, in decreasing frequency, were cardiovascular disease, other nonendocrine tumors > lung diseases, cerebrovascular diseases. The most frequent non-MEN1-related tumor deaths were colorectal, renal > lung > breast, oropharyngeal. Although both overall and disease-related survival are better than in the past (30-yr survival of NIH series: 82% overall, 88% disease-related), the mean age at death was 55 years, which is younger than expected for the general population.Detailed analysis of causes of death correlated with clinical, laboratory, and tumor characteristics of patients in the 2 series allowed identification of a number of prognostic factors. Poor prognostic factors included higher fasting gastrin levels, presence of other functional hormonal syndromes, need for >3 parathyroidectomies, presence of liver metastases or distant metastases, aggressive PET growth, large PETs, or the development of new lesions.The results of this study have helped define the causes of death of MEN1 patients at present, and have enabled us to identify a number of prognostic factors that should be helpful in tailoring treatment for these patients for both short- and long-term management, as well as in directing research efforts to better define the natural history of the disease and the most important factors determining long-term survival at present.

Pharmacotherapy of Zollinger-Ellison syndrome

INTRODUCTION

The role of pharmacotherapy in the management of patients with Zollinger-Ellison syndrome (ZES) is often equated with the medical management of acid hypersecretion. However, pharmacotherapy is also increasingly involved in the other management areas of these patients.

AREAS COVERED

This paper reviews the role of pharmacotherapy in all aspects of the management of patients with ZES. Newer aspects are emphasized. This includes the difficulty of diagnosing ZES in patients taking proton pump inhibitors. Also covered is the role of pharmacotherapy in controlling acid hypersecretion and other hormonal hypersecretory states these patients may develop, including hyperparathyroidism in patients with multiple endocrine neoplasia type 1 and ZES; tumor localization; and the treatment of advanced metastatic disease. The last includes chemotherapy, liver-directed therapies, biotherapy (somatostatin/interferon), peptide radio-receptor therapy and molecular-targeted therapies including the use of mTor inhibitors (everolimus) and tyrosine kinase inhibitors (sunitinib).

EXPERT OPINION

Pharmacotherapy is now involved in all aspects of the management of patients with ZES, with the result that ZES has progressed from being considered an entirely surgical disease initially to the present where medical treatment plays a major role in almost all aspects of the management of these patients.

Current management of the Zollinger-Ellison syndrome

In summary, ZES is a syndrome caused by gastrinoma, usually located within the gastrinoma triangle and associated with symptoms of peptic ulcer disease, GERD, and diarrhea. The diagnosis of ZES is made by measuring fasting levels of serum gastrin, BAO, and the secretin stimulation test. Because of the high association of ZES and MEN1, HPT must be excluded by obtaining a serum calcium and parathyroid hormone level. Treatment of ZES consists of medical control of symptoms with PPIs and evaluation for potentially curative surgical intervention. Noninvasive imaging studies including SRS, CT, and MRI should be performed initially to evaluate for metastases and identify resectable disease. Invasive imaging modalities such as EUS may be performed to further evaluate primary tumors. IOUS, palpation, and duodenotomy are used for intraoperative localization of gastrinomas. In patients with MEN1, surgical resection should be pursued only if there is an identifiable tumor larger than 2 cm and after surgery for the primary hyperparathyroidism (3 1/2-gland parathyroidectomy). All patients with resectable localized sporadic gastrinoma should undergo surgical exploration, even those with biochemical evidence but negative imaging studies. Tumor is most commonly found in the duodenum, and the cure rate is high. In patients with liver metastases, surgery should be considered if all identifiable tumor can be safely removed. A multidisciplinary approach including surgical and nonsurgical therapies should be taken in patients with advanced disease.

Pancreatic neuroendocrine tumors: biology, diagnosis,and treatment

Pancreatic neuroendocrine tumors (PNETs), a group of endocrine tumors arising in the pancreas, are among the most common neuroendocrine tumors. The genetic causes of familial and sporadic PNETs are somewhat understood, but their molecular pathogenesis remains unknown. Most PNETs are indolent but have malignant potential. The biological behavior of an individual PNET is unpredictable; higher tumor grade, lymph node and liver metastasis, and larger tumor size generally indicate a less favorable prognosis. Endocrine testing, imaging, and histological evidence are necessary to accurately diagnose PNETs. A 4-pronged aggressive treatment approach consisting of surgery, locoregional therapy, systemic therapy, and complication control has become popular in academic centers around the world. The optimal application of the multiple systemic therapeutic modalities is under development; efficacy, safety, availability, and cost should be considered when treating a specific patient. The clinical presentation, diagnosis, and treatment of specific types of PNETs and familial PNET syndromes, including the novel Mahvash disease, are summarized.

Importance of surveillance for multiple endocrine neoplasia-1 and surgery in patients with sporadic Zollinger-Ellison syndrome

BACKGROUND & AIMS

Zollinger-Ellison syndrome (ZES) is a rare disorder characterized by gastrin-secreting tumors of the gastrointestinal tract and gastric acid hypersecretion. There is controversy over the best way to manage these patients; we investigated outcomes of patients with different forms of the disease, who did and did not undergo surgery.

METHODS

We performed a retrospective chart review of patients with ZES associated with multiple endocrine neoplasia type 1 (MEN-1) (n = 16) and those with sporadic ZES (n = 33) seen at a tertiary care center from August 1994 to January 2012. Cox proportional hazards modeling was used to compare survival times among groups, based on treatment with surgery (n = 34) and the presence of MEN-1 (n = 9 with surgery; n = 7 without surgery). Differences were compared using the unpaired Student t test and the Fisher exact test.

RESULTS

Patients with MEN-1 syndrome-associated ZES presented at a younger age than patients with sporadic ZES (34.9 vs 45.7 y, respectively; P < .05) and were diagnosed at a younger age (39.3 vs 49.7 y, respectively; P < .01), yet lived a similar number of years (55.9 vs 55.1 y, respectively; P = .91). None of the patients with MEN-1-associated ZES died of progressive disease, compared with 86% of deaths among patients with sporadic ZES (P < .05). Lymph node involvement, detected during surgery, increased the risk of metastasis to liver (P = .13) and lack of cure by surgery (P = .01). Surgery reduced all-cause mortality (hazard ratio, 0.11; 95% confidence interval, 0.2-0.6; P = .011) and disease-related mortality (hazard ratio, 0.14; 95% confidence interval, 0.2-0.84; P = .032) of patients with sporadic, but not MEN-1 syndrome-associated, ZES.

CONCLUSIONS

The presence of MEN-1 is associated with earlier onset and diagnosis of ZES, but a benign clinical course that rarely results in disease-related death; surgery therefore can be deferred for these patients. However, 86% of deaths among patients with sporadic ZES are attributed to disease-related causes, and mortality is reduced by early surgical intervention. Patients with sporadic ZES should undergo surgery soon after diagnosis.

Diagnosis of Zollinger-Ellison syndrome: Increasingly difficult

In the present paper the increasing difficulty of diagnosis of Zollinger-Ellison syndrome (ZES) due to issues raised in two recent papers is discussed. These issues involve the difficulty and need to withdraw patients suspected of ZES from treatment with Proton Pump Inhibitors (omeprazole, esomeprazole, lansoprazole, rabeprazole, pantoprazole) and the unreliability of many gastrin radioimmunoassays. The clinical context of each of these important issues is reviewed and the conclusions in these articles commented from the perspective of clinical management.

Value of surgery in patients with negative imaging and sporadic Zollinger-Ellison syndrome

OBJECTIVES

To address the value of surgery in patients with sporadic Zollinger-Ellison syndrome (ZES) with negative imaging studies.

BACKGROUND

Medical control of acid hypersecretion in patients with sporadic ZES is highly effective. This has led to these patients frequently not being sent to surgery, especially if preoperative imaging studies are negative, due, in large part, to existence of almost no data on the success of surgery in this group.

METHODS

Fifty-eight prospectively studied patients with sporadic ZES (17% of total studied) had negative imaging studies, and their surgical outcome was compared with 117 patients with positive imaging results.

RESULTS

Thirty-five patients had negative imaging studies in the pre-somatostatin receptor scintigraphy (SRS) era, and 23 patients in the post-SRS era. Patients with negative imaging studies had long disease histories before surgery [mean ± SEM (from onset) = 7.9 ± 1 [range, -0.25 to 35 years]) and 25% were followed for 2 or more years from diagnosis. At surgery, gastrinoma was found in 57 of 58 patients (98%). Tumors were small (mean = 0.8 cm, 60% <1 cm). The most common primary sites were duodenal 64%, pancreatic 17%, and lymph node (10%). Fifty percent had a primary-only, 41% primary + lymph node, and 7% had liver metastases. Thirty-five of 58 patients (60%) were cured immediately postoperatively, and at last follow-up [mean = -9.4 years; range, 0.2-22 years], 27 patients (46%) remained cured. During follow-up, 3 patients died, each had liver metastases at surgery. In comparison to positive imaging patients, those with negative imaging studies had lower preoperative fasting gastrin levels; had a longer delay before surgery; more frequently had a small duodenal tumor; less frequently had a pancreatic tumor, multiple tumors, or developed a new lesion postoperatively; and had a longer survival.

CONCLUSIONS

Sporadic ZES patients with negative imaging studies are not rare even in the post-SRS period. An experienced surgeon can find gastrinoma in almost every patient (98%) and nearly one half (46%) are cured, a rate similar to patients with positive imaging findings. Because liver metastases were found in 7%, which may have been caused by a long delay in surgery and all the disease-related deaths occurred in this group, surgery should be routinely undertaken early in ZES patients despite negative imaging studies.

A prospective evaluation of the effect of chronic proton pump inhibitor use on plasma biomarker levels in humans

OBJECTIVE

Proton pump inhibitors (PPIs) are used primarily to treat gastroesophageal reflux disease. Proton pump inhibitor-induced achlorhydria increases circulating gastrin and chromogranin A (CGA). Chromogranin is a widely used biomarker for the diagnosis and follow-up for gut-based neuroendocrine tumors (NETs). Proton pump inhibitor-induced increases in CGA or gastrin may falsely suggest the presence of a NET when none exists. Pancreastatin, a fragment of CGA, is also commonly used to diagnose and follow NETs. We hypothesized that chronic PPI use would increase circulating plasma gastrin, CGA, and pancreastatin levels.

METHODS

Thirty patients who used PPIs for 6 months or more (mean ± SD duration, 3.1 ± 2.5 years) and a separate control group of 30 patients who never used antacid medications were prospectively evaluated with plasma gastrin, CGA, and pancreastatin determinations.

RESULTS

Chronic PPI use resulted in significant increases in CGA (15.1 ± 11 vs 131 ± 207 ng/mL; P = 0.005) and significant increases in gastrin (34.8 ± 22.3 vs 167.8 ± 136.2 pg/mL; P = 0.001) compared to controls. In contrast, pancreastatin level in nonusers and chronic PPI users were identical (81.6 ± 36.4 vs 89.4 ± 43.4 pg/mL; P = 0.46).

CONCLUSIONS

Pancreastatin levels do not change with chronic PPI use and normal pancreastatin levels may be used to distinguish between drug-induced changes in biomarkers and tumor-related increases in circulating biomarkers.

Adrenal involvement in MEN1. Analysis of 715 cases from the Groupe d'etude des Tumeurs Endocrines database

OBJECTIVE

Limited data regarding adrenal involvement in multiple endocrine neoplasia type 1 (MEN1) is available. We describe the characteristics of MEN1-associated adrenal lesions in a large cohort to provide a rationale for their management.

METHODS

Analysis of records from 715 MEN1 patients from a multicentre database between 1956 and 2008. Adrenal lesions were compared with those from a multicentre cohort of 144 patients with adrenal sporadic incidentalomas.

RESULTS

Adrenal enlargement was reported in 20.4% (146/715) of patients. Adrenal tumours (>10 mm in size) accounted for 58.1% of these cases (10.1% of the whole patient cohort). Tumours were bilateral and >40 mm in size in 12.5 and 19.4% of cases respectively. Hormonal hypersecretion was restricted to patients with tumours and occurred in 15.3% of them. Compared with incidentalomas, MEN1-related tumours exhibited more cases of primary hyperaldosteronism, fewer pheochromocytomas and more adrenocortical carcinomas (ACCs; 13.8 vs 1.3%). Ten ACCs occurred in eight patients. Interestingly, ACCs occurred after several years of follow-up of small adrenal tumours in two of the eight affected patients. Nine of the ten ACCs were classified as stage I or II according to the European Network for the Study of Adrenal Tumors. No evident genotype/phenotype correlation was found for the occurrence of adrenal lesions, endocrine hypersecretion or ACC.

CONCLUSIONS

Adrenal pathology in MEN1 differs from that observed in sporadic incidentalomas. In the absence of relevant symptoms, endocrine biology can be restricted to patients with adrenal tumours and should focus on steroid secretion including the aldosterone-renin system. MEN1 is a high-risk condition for the occurrence of ACCs. It should be considered regardless of the size of the tumour.

A novel missense mutation in the MEN1 gene in a patient with multiple endocrine neoplasia type 1

OBJECTIVE

To describe a novel germline missense mutation in exon 2 of the MEN1 gene identified in a man with multiple endocrine neoplasia type 1 (MEN 1).

METHODS

We describe the patient's clinical, laboratory, and genetic data, and we review the relevant literature.

RESULTS

A 41-year-old man with a history of primary hyperparathyroidism and left lower parathyroidectomy presented with nausea, vomiting, and hematemesis. Laboratory data revealed an elevated gastrin level. Computed tomography of the abdomen demonstrated a 3.5-cm mass in the head of pancreas. A functional study with a somatostatin receptor scan showed increased uptake in the region of the pancreatic mass. The patient's symptoms promptly improved after the Whipple procedure, although he was also noted to have a markedly elevated calcium concentration along with inappropriately elevated parathyroid hormone levels. Sestamibi scan identified a hyperfunctioning right upper parathyroid gland. His calcium level normalized after parathyroidectomy, and results from pituitary hormone studies were all normal. Genetic testing of the MEN1 gene identified a novel mutation: Arg52Gly. The Arg52Gly mutation replaces the normal arginine residue (CGC) with a glycine residue (GGC) at position 52 of the resultant menin protein. This mutation was present in family members from 3 generations.

CONCLUSIONS

We report a novel disease-causing germline missense mutation in exon 2 of the MEN1 gene in a patient with MEN 1. Nonconservative replacement of arginine, a small, neutral amino acid, with glycine, a bulky positively charged amino acid, could potentially have a deleterious effect on the menin protein.

Association of long-term proton pump inhibitor therapy with bone fractures and effects on absorption of calcium, vitamin B12, iron, and magnesium

Proton pump inhibitors (PPI) are one of the most widely used classes of drugs. PPIs have a very favorable safety profile, and it is unusual for a patient to stop them because of side effects. However, with increasing numbers of patients chronically taking PPIs for gastroesophageal reflux disease and other common, persistent conditions, the long-term potential adverse effects are receiving increasing attention. An insufficiently studied area receiving much attention is the long-term effect of chronic acid suppression on the absorption of vitamins and nutrients. This increased attention results from the reported potential adverse effect of chronic PPI treatment leading to an increased occurrence of bone fractures. Interest in this area has led to examination of the effects of PPIs on calcium absorption/metabolism and numerous cohort, case-control, and prospective studies of their ability to affect bone density and cause bone fractures. In this article, these studies are systematically examined, as are studies of the effects of chronic PPI use on absorption of VB(12), iron, and magnesium. Studies in each area have led to differing conclusions, but when examined systematically, consistent results of several studies support the conclusion that long-term adverse effects on these processes can have important clinical implications.

New and emerging syndromes due to neuroendocrine tumors

Neuroendocrine tumors (NETs) are rare, slow-growing neoplasms characterized by their ability to store and secrete different peptides and neuroamines. Some of these substances cause specific clinical syndromes whereas others are not associated with specific syndromes or symptom complexes. NETs usually have episodic expression that makes diagnosis difficult, erroneous, and often late. For these reasons a high index of suspicion is needed, and it is important to understand the pathophysiology of each tumor to decide which biochemical markers are more useful and when they should be used.

NANETS treatment guidelines: well-differentiated neuroendocrine tumors of the stomach and pancreas

Well-differentiated neuroendocrine tumors (NETs) of the stomach and pancreas represent 2 major subtypes of gastrointestinal NETs. Historically, there has been little consensus on the classification and management of patients with these tumor subtypes. We provide an overview of well-differentiated NETs of the stomach and pancreas and describe consensus guidelines for the treatment of patients with these malignancies.

Reoperative surgery for the Zollinger-Ellison syndrome

It is clear that a properly performed initial operation is the key to success in the management of a patient with ZES. However, reoperation is frequently a consideration in the management of patients with ZES because high rates of persistent and recurrent disease are manifest even with modern imaging and surgical approaches. In carefully selected patients, reoperation can result in durable biochemical cure and improved survival and should be considered. A thorough knowledge of the natural history of the sporadic form of ZES and ZES in the context of MEN-1, patterns of presentation, and sites of metastases are necessary to achieve the best outcome in patients with this unusual disease.

Surgical management of Zollinger-Ellison syndrome; state of the art

Much has been learned about the diagnosis and treatment of Zollinger-Ellison Syndrome (ZES), and certain questions require further investigation. Delay in diagnosis of ZES is still a significant problem, and clinical suspicion should be elevated. The single best imaging modality for localization and staging of ZES is somatostatin receptor scintigraphy. Goals of surgical treatment for ZES differ between sporadic and MEN-1-related cases. All sporadic cases of ZES should be surgically explored (including duodenotomy) even with negative imaging results, because of the high likelihood of finding and removing a tumor for potential cure. Surgery for MEN-1-related cases should be focused on prevention of metastatic disease, with surgery being recommended when pancreatic tumors are greater than 2 cm. The role of Whipple procedure, especially for MEN-1 cases, should be explored further. Laparoscopic and endoscopic treatments are more experimental, but may have a role.

Five-Year Long-Term Followup of a Primary Lymph node Gastrinoma: Is a Pancreaticoduodenectomy Justified?

Background. Gastrinoma-positive lymph nodes and failed localization of the primary tumor during surgical exploration are described. Specialists suppose that these lymph nodes are metastases rather than a primary gastrinoma. Methods. Case report with a five-year long-term followup. A 60-year-old patient with an confirmed gastrinoma was treated in our department. All preoperative evaluations including somatostatin-receptor-scintigraphy and F-Dopa PET failed to localize the gastrinoma. Explorative laparotomy revealed a gastrinoma in two peripancreatic lymph nodes. Despite extensive intraoperative exploration, no primary gastrinoma could be detected in typical localization. Results. Over a period of 5 years, the patient's gastrin level stayed in the normal range and the patient seems to be completely cured. Conclusion. A prophylactic partial pancreatoduodenectomy is not indicated to avoid recurrence, since complete biochemical cure by local resection of the lymph node gastrinoma is possible.

Genetic testing in other GI diseases

Gastrointestinal development is a complex process comprising folding of the endodermal layer to form the primitive gut tube, cell differentiation along its anteroposterior axis, the budding of the various organ primordia and development of derivative organs like the liver and pancreas and the colonisation of the gut with neuronal precursors. Genetic factors are increasingly recognised as playing a significant role in the disturbance of this developmental process which underlies congenital malformations and gastrointestinal disorders. Furthermore, genetic variation and its interaction with environmental influences play an important role in the pathogenesis of functional gastrointestinal disorders. In this review, we discuss the contribution of genetic variants, ranging from highly penetrant mutations and chromosomal abnormalities to genetic polymorphisms, to the pathogenesis of a number of structural and functional gastrointestinal disorders.

Inherited pancreatic endocrine tumor syndromes: advances in molecular pathogenesis, diagnosis, management, and controversies

Pancreatic endocrine tumors (PETs) can occur as part of 4 inherited disorders, including Multiple Endocrine Neoplasia type 1 (MEN1), von Hippel-Lindau disease (VHL), neurofibromatosis 1 (NF-1) (von Recklinghausen disease), and the tuberous sclerosis complex (TSC). The relative frequency with which patients who have these disorders develop PETs is MEN1>VHL>NF-1>TSC. Over the last few years, there have been major advances in the understanding of the genetics and molecular pathogenesis of these disorders as well in the localization and the medical and surgical treatment of PETs in such patients. The study of PETs in these disorders not only has provided insights into the possible pathogenesis of sporadic PETs but also has presented several unique management and treatment issues, some of which are applicable to patients with sporadic PETs. Therefore, the study of PETs in these uncommon disorders has provided valuable insights that, in many cases, are applicable to the general group of patients with sporadic PETs. In this article, these areas are reviewed briefly along with the current state of knowledge of the PETs in these disorders, and the controversies that exist in their management are summarized briefly and discussed.

Gastrointestinal neuroendocrine tumors: pancreatic endocrine tumors

Pancreatic endocrine tumors (PETs) have long fascinated clinicians and investigators despite their relative rarity. Their clinical presentation varies depending on whether the tumor is functional or not, and also according to the specific hormonal syndrome produced. Tumors may be sporadic or inherited, but little is known about their molecular pathology, especially the sporadic forms. Chromogranin A appears to be the most useful serum marker for diagnosis, staging, and monitoring. Initially, therapy should be directed at the hormonal syndrome because this has the major initial impact on the patient's health. Most PETs are relatively indolent but ultimately malignant, except for insulinomas, which predominantly are benign. Surgery is the only modality that offers the possibility of cure, although it generally is noncurative in patients with Zollinger-Ellison syndrome or nonfunctional PETs with multiple endocrine neoplasia-type 1. Preoperative staging of disease extent is necessary to determine the likelihood of complete resection although debulking surgery often is believed to be useful in patients with unresectable tumors. Once metastatic, biotherapy is usually the first modality used because it generally is well tolerated. Systemic or regional therapies generally are reserved until symptoms occur or tumor growth is rapid. Recently, a number of newer agents, as well as receptor-directed radiotherapy, are being evaluated for patients with advanced disease. This review addresses a number of recent advances regarding the molecular pathology, diagnosis, localization, and management of PETs including discussion of peptide-receptor radionuclide therapy and other novel antitumor approaches. We conclude with a discussion of future directions and unsettled problems in the field.

Somatostatin stimulates menin gene expression by inhibiting protein kinase A

Somatostatin is a potent inhibitor of gastrin secretion and gene expression. Menin is a 67-kDa protein product of the multiple endocrine neoplasia type 1 (MEN1) gene that when mutated leads to duodenal gastrinomas, a tumor that overproduces the hormone gastrin. These observations suggest that menin might normally inhibit gastrin gene expression in its role as a tumor suppressor. Since somatostatin and ostensibly menin are both inhibitors of gastrin, we hypothesized that somatostatin signaling directly induces menin. Menin protein expression was significantly lower in somatostatin-null mice, which are hypergastrinemic. We found by immunohistochemistry that somatostatin receptor-positive cells (SSTR2A) express menin. Mice were treated with the somatostatin analog octreotide to determine whether activation of somatostatin signaling induced menin. We found that octreotide increased the number of menin-expressing cells, menin mRNA, and menin protein expression. Moreover, the induction by octreotide was greater in the duodenum than in the antrum. The increase in menin observed in vivo was recapitulated by treating AGS and STC cell lines with octreotide, demonstrating that the regulation was direct. The induction required suppression of protein kinase A (PKA) since forskolin treatment suppressed menin protein levels and octreotide inhibited PKA enzyme activity. Small-interfering RNA-mediated suppression of PKA levels raised basal levels of menin protein and prevented further induction by octreotide. Using AGS cells, we also showed for the first time that menin directly inhibits endogenous gastrin gene expression. In conclusion, somatostatin receptor activation induces menin expression by suppressing PKA activation.

Giant gastrinoma in a child: case report and review

Gastrinomas are rare neuroendocrine tumours. A 9-year-old boy who initially presented with recurrent upper abdominal pain and was managed as hyperacidity syndrome was later diagnosed to have a primary, retroperitoneal, extra pancreatic gastrinoma after an asymptomatic period of 6 years is presented. At the second presentation, the contrast-enhanced CT revealed an epigastric mass and serum gastrin was grossly elevated. A complete excision of the mass was done; histopathological evaluation showed a well-differentiated neuroendocrine tumour. At a year follow up, the child is asymptomatic and the review imaging and serum gastrin levels are normal.

Primary lymph node gastrinoma or occult duodenal microgastrinoma with lymph node metastases in a MEN1 patient: the need for a systematic search for the primary tumor

Gastrinoma tissue has been found frequently in lymph nodes located near the duodenum without a known primary tumor. Therefore, it has been suggested that a primary lymph node gastrinoma exists. We report on a 38-year-old woman suffering from multiple endocrine neoplasia type 1 (MEN1) confirmed by menin gene mutation analysis. MEN1 disease started with primary hyperparathyroidism followed by Cushing disease, the detection of tumors of the pituitary, adrenal cortex, and the pancreas and also an elevated serum gastrin level. An octreotide scan revealed 4 tumors in the upper abdomen. A selective arterial calcium stimulation test located the source of the hypergastrinemia to the area of the gastroduodenal and the superior mesenteric arteries. Total pancreatoduodenectomy was performed and conventional histopathologic examination revealed a well-differentiated cystic neuroendocrine tumor of the pancreas expressing glucagon and accompanied by several microadenomas. In addition, 3 suprapancreatic lymph nodes with gastrin-positive endocrine tissue were found. None of the pancreatic microadenomas expressed gastrin and no duodenal endocrine tumor was found despite careful macroscopic examination. Only after complete embedding of the duodenal and pancreatic tissue in 65 paraffin blocks, 2 microgastrinomas (0.45 and 0.8 mm in diameter) were identified in the duodenum. It is concluded that duodenal gastrinomas that give rise to lymph node metastases may be so tiny that they are easily overlooked in a routine examination and that systematic tissue monitoring is required to identify them.

Pancreatic endocrine neoplasms: epidemiology and prognosis of pancreatic endocrine tumors

Pancreatic endocrine tumors (PETs) are uncommon tumors with an annual incidence <1 per 100 000 person-years in the general population. The PETs that produce hormones resulting in symptoms are designated as functional. The majority of PETs are non-functional. Of the functional tumors, insulinomas are the most common, followed by gastrinomas. The clinical course of patients with PETs is variable and depends on the extent of the disease and the treatment rendered. Patients with completely resected tumors generally have a good prognosis, and aggressive surgical therapy in patients with advanced disease may also prolong survival. The epidemiology, prognosis, and established and novel prognostic markers of PETs are reviewed.

Prospective study of surgery for primary hyperparathyroidism (HPT) in multiple endocrine neoplasia-type 1 and Zollinger-Ellison syndrome: long-term outcome of a more virulent form of HPT

BACKGROUND

Primary hyperparathyroidism (HPT) in multiple endocrine neoplasia type 1 (MEN1) patients with Zollinger-Ellison syndrome (ZES) is caused by parathyroid hyperplasia. Surgery for parathyroid hyperplasia is tricky and difficult. Long-term outcome in ZES/MEN1/HPT is not well known.

METHODS

Eighty-four consecutive patients (49 F/35 M) with ZES/MEN1/HPT underwent initial parathyroidectomy (PTX) and were followed at 1- to 3-year intervals.

RESULTS

Age at PTX was 36 +/- 2 years. Mean follow-up was 17 +/- 1 years. Before PTX, mean Ca = 2.8 mmol/L (normal level (nl <2.5), PTH i = 243 pg/mL (nl <65), and gastrin = 6950 pg/mL (nl < 100). Sixty-one percent had nephrolithiasis. Each patient had parathyroid hyperplasia. Fifty-eight percent of patients had 4 parathyroid glands identified. Nine of 84 (11%) had 4 glands removed with immediate autograft, 40/84 (47%) 3 to 3.5 glands, whereas 35/84 (42%) <3 glands removed. Persistent/recurrent HPT occurred in 42%/48% of patients with <3 glands, 12%/44% with 3 to 3.5 glands, and 0%/55% with 4 glands removed. Hypoparathyroidism occurred in 3%, 10%, and 22%, respectively. The disease-free interval after surgery was significantly longer if >3 glands were removed. After surgery to correct the HPT, each biochemical parameter of ZES was improved and 20% of patients no longer had laboratory evidence of ZES.

CONCLUSIONS

HPT/MEN1/ZES is a severe form of parathyroid hyperplasia with a high rate of nephrolithiasis, persistent and recurrent HPT. Surgery to correct the hypercalcemia significantly ameliorates the ZES. Removal of less than 3.5 glands has an unacceptably high incidence of persistent HPT (42%), whereas 4-gland resection and transplant has a high rate of permanent hypoparathyroidism (22%). More than 3-gland resection has a longer disease-free interval. The surgical procedure of choice for patients with HPT/MEN1/ZES is 3.5-gland parathyroidectomy. Careful long-term follow-up is necessary as a significant proportion will develop recurrent HPT.

Diagnosis and treatment of gastrinoma in the era of proton pump inhibitors

The Zollinger-Ellison syndrome is characterized pathophysiologically by a significant hypergastrinemia derived from a gastrin-secreting neuroendocrine tumor with a primary location in the pancreas or duodenum. Chronic hypergastrinemia in turn triggers gastric acid hypersecretion yielding in chronic or recurrent or refractory peptic ulcer disease and/or chronic diarrhea. One half of patients with ZES will have distant metastases in the liver by the time the diagnosis is established and one half of all patients with ZES will experience chronic diarrhea as chief complaint rather than peptic ulcer-related symptoms and signs. Gastrinomas have been reported to either manifest sporadically or to occur in conjunction with the genetic background of the MEN-I syndrome. Diagnosis is based on the patients history which is typically characterized by recurrent episodes of peptic ulcer disease or by severe reflux esophagitis and/or diarrhea or by acid-related symptoms which fail to respond to standard treatment regimens. Upper gastrointestinal tract endoscopy will provide evidence for peptic ulcer disease in anatomical regions located aborally the duodenal bulb within the descending part of the duodenum or even farther distally within the jejunum. Peptic ulcers frequently occur in groups indicating some substantial acid hypersecretion. A gastric pH > 2 is mutually exclusive for ZES. Increased serum gastrin levels confirm the diagnosis biochemically. Gastrin secretion can be determined in the basal state or following stimulation with secretin or calcium. High sensitivity and specificity for the diagnosis of ZES is provided by determining the ratio of basal versus pentagastrin-stimulated gastric acid secretion: The ratio of BAO / MAO > 0.6 is highly specific for gastrinoma. To localize the gastrin-secreting tumor computer-assisted tomography, endoscopic ultrasound, and somatostatin receptor scintigraphy provide useful help but most recently, endoscopic ultrasound with high resolution transducers appear to improve preoperative site localization. If modern imaging techniques fail to elucidate the site of the tumor, intraoperative diaphany may help to detect gastrinomas within the duodenal wall. Definitive treatment will only be achieved by total surgical resection of the gastrin-producing tumor in the pancreas or duodenum including dissection of the regional lymph nodes. Control of symptoms will have to be achieved by administration of highly potent proton pump inhibitors in up to 2-3-fold increased standard doses to inhibit gastric acid hypersecretion. Elevation of gastric pH > 4 will be the therapeutic target to protect the mucosa of the upper gastrointestinal tract. Basal acid output should be reduced to less than 10 mEq H(+) per hour which requires administration of highly potent proton pump inhibitors with a recommended starting dose of 60 mg omeprazole equivalents per day.

Surgery for gastrinoma

Surgery has been demonstrated to offer potential for cure in patients who have sporadic ZES and improved tumor-related survival in all patients who have ZES with gastrinomas larger than 2.5 cm. Techniques such as preoperative localization with SRS and intraoperative localization with duodenotomy have improved the effectiveness of surgical intervention for ZES. Future directions for investigation should include better defining the role of preoperative EUS and developing new, more sensitive techniques for preoperative localization. More research also is needed to define the appropriate indications for pancreaticoduodenectomy in ZES and to determine whether proximal vagotomy should be performed at the time of surgical exploration.

Biochemistry of neuroendocrine tumours

Several circulating or urinary tumour markers can be used for the diagnosis and follow-up of functioning and clinically non-functioning neuroendocrine tumours of the pancreatic islet cells and intestinal tract. Among the specific tumour markers are serotonin and its metabolites--e.g. 5-hydroxyindoleacetic acid (5-HIAA)--in carcinoid tumours and the carcinoid syndrome, insulin and its precursors or breakdown products in insulinoma, and gastrin in gastrinoma. Plasma vasointestinal polypeptide (VIP) determinations have been used in the diagnosis of VIPoma, plasma glucagon for glucagonoma, and serum somatostatin for somatostatinoma. Among the tumour-non-specific markers are: chromogranins, neuron-specific enolase (NSE), alpha-subunits of the glycoprotein hormones, catecholamines, pancreatic polypeptide (PP), ghrelin and adrenomedullin.

Role of CCK/gastrin receptors in gastrointestinal/metabolic diseases and results of human studies using gastrin/CCK receptor agonists/antagonists in these diseases

In this paper, the established and possible roles of CCK1 and CCK2 receptors in gastrointestinal (GI) and metabolic diseases are reviewed and available results from human agonist/antagonist studies are discussed. While there is evidence for the involvement of CCK1R in numerous diseases including pancreatic disorders, motility disorders, tumor growth, regulation of satiety and a number of CCK-deficient states, the role of CCK1R in these conditions is not clearly defined. There are encouraging data from several clinical studies of CCK1R antagonists in some of these conditions, but their role as therapeutic agents remains unclear. The role of CCK2R in physiological (atrophic gastritis, pernicious anemia) and pathological (Zollinger-Ellison syndrome) hypergastrinemic states, its effects on the gastric mucosa (ECL cell hyperplasia, carcinoids, parietal cell mass) and its role in acid-peptic disorders are clearly defined. Furthermore, recent studies point to a possible role for CCK2R in a number of GI malignancies. Current data from human studies of CCK2R antagonists are presented and their potential role in the treatment of these conditions reviewed. Furthermore, the role of CCK2 receptors as targets for medical imaging is discussed.

A case of recurrent renal failure associated with metabolic alkalosis induced by protracted vomiting

We describe a case of recurrent deterioration of renal function in a 54-year-old man who was found to have metabolic alkalosis, with a maximum PaCO(2) of 73.9 mmHg and a bicarbonate concentration of 55.3 mmol/l. He had a gradual exacerbation of nausea and vomiting due to atrophic gastritis, with a scarred, deformed pyloric part of the stomach and a duodenal bulb secondary to chronic peptic ulcer. His metabolic alkalosis and deteriorated renal function were corrected by intravenous saline with or without potassium chloride. However, his recovered creatinine clearance was at most 60 l/day (41.6 ml/min). A renal biopsy revealed cellular infiltration of mononuclear cells and atrophic change in the tubulointerstitium, suggesting chronic interstitial nephritis. Latent renal insufficiency and dehydration induced by protracted vomiting may easily induce a rapid and recurrent deterioration of renal function, and control of vomiting seemed to be the cardinal measure. Initially, his nausea and vomiting seemed to be successfully controlled by medication, however, they later became persistent and surgical correction of the stomach was carried out. Postoperative recovery was smooth, and the patient's vomiting and recurrent deterioration of renal function finally settled.

Canine gastrinoma: a case study and literature review of therapeutic options

CASE HISTORY

A 6.2 kg, 8-year-old, spayed female Australian Terrier was presented with weight loss, inappetence, lethargy and a 2-day history of intermittent vomiting.

CLINICAL FINDINGS

The dog had cranial abdominal pain and there was melaena present on digital rectal examination. Haematology revealed a marked, acute leucogram.

DIAGNOSIS AND TREATMENT

Fasting serum gastrin levels were markedly elevated and gastrinoma was suspected. Treatment was initiated with omeprazole, ranitidine and sucralfate. The dog remained clinically normal for 26 months, at which time exploratory surgery was undertaken and the dog subsequently euthanised due to extensive metastases. Histopathology and immunocytochemistry confirmed the diagnosis of metastatic gastrinoma.

CLINICAL RELEVANCE

This is a rare condition infrequently reported. Although the number of cases treated with omeprazole are too few to draw firm conclusions, it would appear that proton pump inhibitors are useful and should be considered for cases of gastrinoma managed medically. Long-term prognosis is poor, and survival times range from 1 to 147 weeks. Many treatment options are discussed in the medical literature though not all are feasible in veterinary patients.

Serum gastrin in Zollinger-Ellison syndrome: II. Prospective study of gastrin provocative testing in 293 patients from the National Institutes of Health and comparison with 537 cases from the literature. evaluation of diagnostic criteria, proposal of new criteria, and correlations with clinical and tumoral features

In two-thirds of patients with Zollinger-Ellison syndrome (ZES), fasting serum gastrin (FSG) levels overlap with values seen in other conditions. In these patients, gastrin provocative tests are needed to establish the diagnosis of ZES. Whereas numerous gastrin provocative tests have been proposed, only the secretin, calcium, and meal tests are widely used today. Many studies have analyzed gastrin provocative test results in ZES, but they are limited by small patient numbers and methodologic differences. To address this issue, we report the results of a prospective National Institutes of Health (NIH) study of gastrin provocative tests in 293 patients with ZES and compare these data with those from 537 ZES and 462 non-ZES patients from the literature. In 97%-99% of gastrinoma patients, an increase in serum gastrin post secretin (Delta secretin) or post calcium (Delta calcium) occurred. In NIH ZES patients with <10-fold increase in FSG, the sensitivity/specificity of the widely used criteria were as follows: Delta secretin > or =200 pg/mL (83%/100%), Delta secretin >50% (86%/93%), Delta calcium > or =395 pg/mL (54%/100%), and Delta calcium >50% (78%/83%). A systematic analysis of the sensitivity and specificity of other possible criteria for a positive secretin or calcium test allowed us to identify a new criterion for secretin testing (Delta > or =120 pg/mL) with the highest sensitivity/specificity (94%/100%) and to confirm the commonly used criterion for calcium tests (Delta > or =395 pg/mL) (62%/100%). This analysis further showed that the secretin test was more sensitive than the calcium test (94% vs. 62%). Our results suggest that secretin stimulation should be used as the first-line provocative test because of its greater sensitivity and simplicity and lack of side effects. In ZES patients with a negative secretin test, 38%-50% have a positive calcium test. Therefore the calcium test should be considered in patients with a strong clinical suspicion of ZES but a negative secretin test. Furthermore, we found that some clinical (diarrhea, duration of medical treatment), laboratory (basal acid output), and tumoral (size, extent) characteristics correlate with the serum gastrin increase post secretin and post calcium. However, using the proposed criteria, the result of these provocative tests (that is, positive or negative) is minimally influenced by these factors, so secretin and calcium provocative tests are reliable in patients with different clinical, laboratory, and tumor characteristics. A systematic analysis of meal testing showed that 54%-77% of ZES patients have a <50% postprandial serum gastrin increase. However, 9%-20% of ZES patients had a >100% increase post meal, causing significant overlap with antral syndromes. Furthermore, we could not confirm the usefulness of meal tests for localization of duodenal gastrinomas. We conclude that the secretin test is a crucial element in the diagnosis of most ZES patients, the calcium test may be useful in selected patients, but the meal test is not helpful in the management of ZES. For secretin testing, the criterion with the highest sensitivity and specificity is an increase of > or =120 pg/mL, which should replace other criteria commonly used today.