Functional imaging in hyperinsulinemic hypoglycemia after gastric bypass surgery for morbid obesity

Diffuse, Adult-Onset Nesidioblastosis/Non-Insulinoma Pancreatogenous Hypoglycemia Syndrome (NIPHS): Review of the Literature of a Rare Cause of Hyperinsulinemic Hypoglycemia

Differential diagnosis of hypoglycemia in the non-diabetic adult patient is complex and comprises various diseases, including endogenous hyperinsulinism caused by functional β-cell disorders. The latter is also designated as nesidioblastosis or non-insulinoma pancreatogenous hypoglycemia syndrome (NIPHS). Clinically, this rare disease presents with unspecific adrenergic and neuroglycopenic symptoms and is, therefore, often overlooked. A combination of careful clinical assessment, oral glucose tolerance testing, 72 h fasting, sectional and functional imaging, and invasive insulin measurements can lead to the correct diagnosis. Due to a lack of a pathophysiological understanding of the condition, conservative treatment options are limited and mostly ineffective. Therefore, nearly all patients currently undergo surgical resection of parts or the entire pancreas. Consequently, apart from faster diagnosis, more elaborate and less invasive treatment options are needed to relieve the patients from the dangerous and devastating symptoms. Based on a case of a 23-year-old man presenting with this disease in our department, we performed an extensive review of the medical literature dealing with this condition and herein presented a comprehensive discussion of this interesting disease, including all aspects from epidemiology to therapy.

Radiosynthesis, Preclinical, and Clinical Positron Emission Tomography Studies of Carbon-11 Labeled Endogenous and Natural Exogenous Compounds

The presence of positron emission tomography (PET) centers at most major hospitals worldwide, along with the improvement of PET scanner sensitivity and the introduction of total body PET systems, has increased the interest in the PET tracer development using the short-lived radionuclides carbon-11. In the last few decades, methodological improvements and fully automated modules have allowed the development of carbon-11 tracers for clinical use. Radiolabeling natural compounds with carbon-11 by substituting one of the backbone carbons with the radionuclide has provided important information on the biochemistry of the authentic compounds and increased the understanding of their in vivo behavior in healthy and diseased states. The number of endogenous and natural compounds essential for human life is staggering, ranging from simple alcohols to vitamins and peptides. This review collates all the carbon-11 radiolabeled endogenous and natural exogenous compounds synthesised to date, including essential information on their radiochemistry methodologies and preclinical and clinical studies in healthy subjects.

The Role of Positron Emission Tomography in Bariatric Surgery Research: a Review

Bariatric surgery, initially understood as restricting or bypassing the amount of food that reaches the stomach to reduce food intake and/or increase malabsorption of food to promote weight loss, is now recognized to also affect incretin signaling in the gut and promote improvements in system-wide metabolism. Positron emission tomography (PET) is an imaging technique whereby patients are injected with picomolar concentrations of radioactive molecules, below the threshold of having physiological effects, to measure spatial distributions of blood flow, metabolism, receptor, and enzyme pharmacology. Recent advances in both whole-body PET imaging and radioligand development will allow for novel research that may help clarify the roles of peripheral and central receptor/enzyme systems in treating obesity with bariatric surgery.

Hypoglycemia Worsened by Glucose Administration: A Case of Hypoglycemia Years After Gastric Surgery

BACKGROUND

Noninsulinoma pancreatogenous hypoglycemia syndrome (NIPHS) is a rare syndrome characterized by postprandial hypoglycemia with neuroglycopenic symptoms occurring 1 to 3 h after a meal. Diagnosis can be elusive, as the vast majority of patients have normal fasting blood glucose levels, and onset of hypoglycemic episodes can be a late complication of gastric surgery.

CASE REPORT

We report the case of a 45-year-old woman presenting to the Emergency Department (ED) with new-onset seizures and hypoglycemia worsened by glucose administration. Surgical history is pertinent for a Roux-en-Y gastric bypass approximately 10 years prior to presentation. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Although rare, it is important for emergency physicians to be vigilant of this disease process as a traditional treatment approach for hypoglycemia may be detrimental. Although cases of NIPHS have been documented in literature, its presence in emergency medicine-specific literature is seemingly nonexistent. Noninvasive imaging techniques will be normal, and diagnosis is dependent on awareness of this disease entity coupled with a detailed history.

International consensus on the diagnosis and management of dumping syndrome

Dumping syndrome is a common but underdiagnosed complication of gastric and oesophageal surgery. We initiated a Delphi consensus process with international multidisciplinary experts. We defined the scope, proposed statements and searched electronic databases to survey the literature. Eighteen experts participated in the literature summary and voting process evaluating 62 statements. We evaluated the quality of evidence using grading of recommendations assessment, development and evaluation (GRADE) criteria. Consensus (defined as >80% agreement) was reached for 33 of 62 statements, including the definition and symptom profile of dumping syndrome and its effect on quality of life. The panel agreed on the pathophysiological relevance of rapid passage of nutrients to the small bowel, on the role of decreased gastric volume capacity and release of glucagon-like peptide 1. Symptom recognition is crucial, and the modified oral glucose tolerance test, but not gastric emptying testing, is useful for diagnosis. An increase in haematocrit >3% or in pulse rate >10 bpm 30 min after the start of the glucose intake are diagnostic of early dumping syndrome, and a nadir hypoglycaemia level <50 mg/dl is diagnostic of late dumping syndrome. Dietary adjustment is the agreed first treatment step; acarbose is effective for late dumping syndrome symptoms and somatostatin analogues are preferred for patients who do not respond to diet adjustments and acarbose.

Dumping syndrome after esophageal, gastric or bariatric surgery: pathophysiology, diagnosis, and management

BACKGROUND

Dumping syndrome, a common complication of esophageal, gastric or bariatric surgery, includes early and late dumping symptoms. Early dumping occurs within 1 h after eating, when rapid emptying of food into the small intestine triggers rapid fluid shifts into the intestinal lumen and release of gastrointestinal hormones, resulting in gastrointestinal and vasomotor symptoms. Late dumping occurs 1-3 h after carbohydrate ingestion, caused by an incretin-driven hyperinsulinemic response resulting in hypoglycemia. Clinical recommendations are needed for the diagnosis and management of dumping syndrome.

METHODS

A systematic literature review was performed through February 2016. Evidence-based medicine was used to develop diagnostic and management strategies for dumping syndrome.

RESULTS

Dumping syndrome should be suspected based on concurrent presentation of multiple suggestive symptoms after upper abdominal surgery. Suspected dumping syndrome can be confirmed using symptom-based questionnaires, glycemia measurements and oral glucose tolerance tests. First-line management of dumping syndrome involves dietary modification, as well as acarbose treatment for persistent hypoglycemia. If these approaches are unsuccessful, somatostatin analogues should be considered in patients with dumping syndrome and impaired quality of life. Surgical re-intervention or continuous enteral feeding may be necessary for treatment-refractory dumping syndrome, but outcomes are variable.

CONCLUSIONS

Implementation of these diagnostic and treatment recommendations may improve dumping syndrome management.

Pancreatic Uptake by 18F-FDOPA PET/CT in Patients With Hypoglycemia After Gastric Bypass Surgery Compared With Controls With or Without Carbidopa Pretreatment

PURPOSE

The use of Fluorine-labeled dihydroxy-phenyl-alanine (F-FDOPA) PET/CT in patients with hypoglycemia suspected to be caused by pancreatic disease can be helpful to localize the source of excess insulin production. In this setting, carbidopa pretreatment is not recommended. However, quantitative comparisons of pancreatic tracer uptake in patients with or without carbidopa pretreatment and in diffuse pancreatic disease are lacking. Therefore, we aimed to describe and quantify pancreatic F-FDOPA uptake in patients without pancreatic disease with or without carbidopa pretreatment and in patients with hypoglycemia after gastric bypass surgery.

PATIENTS AND METHODS

This is a retrospective data analysis of F-FDOPA PET/CT scans performed at a university medical center in the period from 2009 to 2015. All scans were reconstructed and calculated based on the European Association of Nuclear Medicine/EANM Research Ltd guidelines. Of 358 patients without evidence of pancreatic disease or hypoglycemic disorders, 344 received carbidopa and 14 did not. Another 9 patients had post-gastric bypass hypoglycemia. The main outcome measurement was F-FDOPA SUVmax for pancreatic head, body, and tail regions.

RESULTS

Carbidopa pretreated patients had a lower median SUVmax (-1.15, -1.20, and -0.84 in pancreatic head, body, and tail [all P < 0.01]) than patients without carbidopa pretreatment. Patients with post-gastric bypass hypoglycemia scanned without carbidopa pretreatment had higher median SUVmax (+1.18, +1.39, and +1.63, all P < 0.03) compared with controls without pretreatment.

CONCLUSIONS

Patients with post-gastric bypass hypoglycemia have increased uptake in all pancreatic regions. Carbidopa pretreatment lowers pancreatic F-FDOPA uptake in the nonaffected pancreas and may therefore mask disease activity in post-gastric bypass hypoglycemia.

Diagnostic tools for post-gastric bypass hypoglycaemia

In spite of its evident success, several late complications can occur after gastric bypass surgery. One of these is post-gastric bypass hypoglycaemia. No evidence-based guidelines exist in the literature on how to confirm the presence of this syndrome. This study aims to describe and compare the tests aimed at making a diagnosis of post-gastric bypass hypoglycaemia and to provide a diagnostic approach based upon the available evidence. A search was conducted in PubMed, Cochrane and Embase. A few questionnaires have been developed to measure the severity of symptoms in post-gastric bypass hypoglycaemia but none has been validated. The gold standard for provocation of a hypoglycaemic event is the oral glucose tolerance test or the liquid mixed meal tolerance test. Both show a high prevalence of hypoglycaemia in post-gastric bypass patients with and without hypoglycaemic complaints as well as in healthy volunteers. No uniformly established cut-off values for glucose concentrations are defined in the literature for the diagnosis of post-gastric bypass hypoglycaemia. For establishing an accurate diagnosis of post-gastric bypass hypoglycaemia, a validated questionnaire, in connection with the diagnostic performance of provocation tests, is the most important thing missing. Given these shortcomings, we provide recommendations based upon the current literature.

Role of (18) F-FDOPA PET/CT imaging in endocrinology

(18) F-FDOPA (6-[18F]-L-fluoro-L-3, 4-dihydroxyphenylalanine)-based PET/CT imaging can be a useful tool for the detection of different neuroendocrine tumours (NETs). (18) F-FDOPA is taken up into the cells via the neutral amino acid transporter (LAT1/4F2hc). This transporter is also coupled to the mammalian target of rapamycin (mTOR) signalling pathway. (18) F-FDOPA PET/CT may be performed for confirmation of diagnosis of pheochromocytoma/paraganglioma, staging at initial presentation, restaging and follow-up of patients. In SDHx-related syndromes, (18) F-FDG PET/CT should be performed in addition to (18) F-FDOPA PET/CT. (18) F-FDOPA PET/CT is also invaluable in the detection staging/restaging of carcinoid tumours and has greater sensitivity as compared to somatostatin receptor scintigraphy. (18) F-FDOPA PET/CT can also distinguish between focal vs diffuse CHI. It is not as useful in adult hyperinsulinism due to increased background uptake, but the problem may be overcome with the help of premedication with carbidopa. It has limited use in pancreatic NETs. (18) F-FDOPA PET/CT is a good modality for detection of persistent and residual medullary thyroid cancer (MTC), but (18) F-FDG PET/CT may be needed in aggressive tumours. In summary, F-DOPA PET/CT has widespread utility in the diagnosis of different neuroendocrine tumours.

Hypoglycemia after Roux-En-Y gastric bypass: detection rates of continuous glucose monitoring (CGM) versus mixed meal test

BACKGROUND

Neuroglucopenic hypoglycemia might be an underestimated threat for roux-en-Y gastric bypass (RYGB) patients leading to fatigue, syncope, seizures or even accidental deaths. Different measurements can assess hypoglycemia such as a finger-stick glucometer, an Oral Glucose Tolerance Test, a Mixed Meal-Test (MMT) or, as introduced recently, continuous glucose monitoring (CGM).

SETTING

University Hospital, Austria.

METHODS

To assess the incidence of hypoglycemic episodes under real life conditions, 5-day CGM was performed in a series of 40 patients at a mean of 86 months after RYGB. The detection rates were compared to a mixed meal-test.

RESULTS

CGM detected hypoglycemic episodes of <55 mg/dL or <3.05 mmol/L in 75% of the patients, while MMT indicated hypoglycemia in 29% of the patients. CGM also detected nocturnal hypoglycemic episodes in 15 (38%) of the patients. A mean of 3±1 hypoglycemic episodes per patient with a mean duration of 71±25 minutes were observed by CGM.

CONCLUSIONS

Assessed under real life conditions by CGM, post-RYGB hypoglycemia was found more frequently than expected. CGM revealed hypoglycemic episodes in 75% of the patients while MMT had a lower detection rate. Thus, CGM may have a role for screening but also for the evaluation of dietary modifications, drug therapy or surgical intervention for hypoglycemia after RYGB.

Postprandial hyperinsulinemic hypoglycemia after gastric bypass surgical treatment

An association between post-Roux-en-Y gastric bypass (RYGB) hypoglycemia and nesidioblastosis was reported in 2005 and may cause serious neuroglycopenic symptoms. Most patients with postprandial hypoglycemia after RYGB respond to nutritional and medical treatment. A subset of patients, however, may not respond adequately and surgery may be considered. This review describes the current experience with surgical intervention for severe post-RYGB hypoglycemia. PubMed and MEDLINE searches were made for reports describing clinical outcome after such surgery. Fourteen papers including 75 patients were identified. Different surgical interventions were applied including gastric tube placement, reversal of the bypass with and without concomitant sleeve resection, gastric pouch restriction, and pancreatic resection and reresection. Pancreatic resection was performed in 51 (68%) patients, 17 (23%) had RYGB reversal and eleven (15%) had gastric pouch restriction alone. Eight (11%) patients received 2 or more consecutive procedures for hypoglycemia and combined interventions were made in several patients. Resolution of the symptoms occurred in 34/51 (67%) patients after pancreatic resection, 13/17 (76%) after reversal, and 9/11 (82%) after pouch restriction. Mean follow up, however, was short for most series and the methods applied for evaluation of hypoglycemia varied. Weight regain, diabetes and recurrent symptoms were late complications. The optimal therapy for hypoglycemia after RYGB is not defined. Long-term evaluations and knowledge about the physiology of post-RYGB hypoglycemia, may enable therapy with improved control of the glucose excursions.