Diagnostic approach to adults with hypoglycemic disorders

An extremely rare case of hypoglycemia with a novel mutation and review of the literature: fructose-1,6 bisphosphatase deficiency in an adult man

Hypoglycemia is an uncommon clinical problem among non-diabetic patients. It requires systematic evaluation to determine the etiology. It may be related to critical illness, hepatic insufficiency, renal insufficiency, cardiac insufficiency, drugs, alcohol, cortisol insufficiency, growth hormone insufficiency, insulinoma, gastric bypass surgery, and paraneoplastic (insulin-like growth factor-2-related) immune-mediated or inherited metabolic disorders. We aimed to summarize the literature and present a case who suffered from hypoglycemia throughout his life and was diagnosed with fructose-1, 6 bisphosphatase deficiency in adulthood to attract attention to the rare causes of hypoglycemia in adulthood.

European Neuroendocrine Tumor Society 2023 guidance paper for functioning pancreatic neuroendocrine tumour syndromes

This ENETS guidance paper aims to provide practical advice to clinicians for the diagnosis, treatment and follow-up of functioning syndromes in pancreatic neuroendocrine tumours (NET). A NET-associated functioning syndrome is defined by the presence of a clinical syndrome combined with biochemical evidence of inappropriately elevated hormonal levels. Different hormonal syndromes can be encountered in pancreatic NET patients, including insulinoma, gastrinoma as well as the rare glucagonoma, VIPoma, ACTHoma, PTHrPoma, carcinoid syndrome, calcitoninoma, GHRHoma and somatostatinoma. The recommendations provided in this paper focus on the biochemical, genetic and imaging work-up as well as therapeutic management of the individual hormonal syndromes in well-differentiated, grade 1-3, functioning NET with the primary tumour originating in the pancreas, and for specific subtypes also in the duodenum.

Clinical Presentation and Diagnostic Approach to Hypoglycemia in Adults Without Diabetes Mellitus

OBJECTIVE

To review the clinical presentation, causes, and diagnostic approach to spontaneous hypoglycemia in adults without diabetes mellitus.

METHODS

A literature review was performed using the PubMed and Google Scholar databases.

RESULTS

Hypoglycemia is uncommon in people who are not on glucose-lowering medications. Under normal physiologic conditions, multiple neural and hormonal counterregulatory mechanisms prevent the development of abnormally low levels of plasma glucose. If spontaneous hypoglycemia is suspected, the Whipple triad should be used to confirm hypoglycemia before pursuing further diagnostic workup. The Whipple criteria include the following: (1) low levels of plasma glucose, (2) signs or symptoms that would be expected with low levels of plasma glucose, and (3) improvement in those signs or symptoms when the level of plasma glucose increases. Spontaneous hypoglycemia can be caused by conditions that cause endogenous hyperinsulinism, including insulinoma, postbariatric hypoglycemia, and noninsulinoma pancreatogenous hypoglycemia. Spontaneous hypoglycemia can also be seen with critical illness, hepatic or renal dysfunction, hormonal deficiency, non-diabetes-related medications, and non-islet cell tumors. The initial diagnostic approach should begin by obtaining a detailed history of the nature and timing of the patient's symptoms, medications, underlying comorbid conditions, and any acute illness. A laboratory evaluation should be conducted at the time of the spontaneous symptomatic episode. Supervised tests such as a 72-hour fast or mixed-meal test may be needed to recreate the situation under which the patient is likely to experience symptoms.

CONCLUSION

We provide an overview of the physiology of counterregulatory response to hypoglycemia, its causes, and diagnostic approaches to spontaneous hypoglycemia in adults.

Evaluation and Management of Patients Referred for Post-Bariatric Surgery Hypoglycemia at a Tertiary Care Center

PURPOSE

Following bariatric surgery, patients can develop non-specific symptoms self-described as hypoglycemia. However, confirming hypoglycemia can be technically challenging, and therefore, these individuals are frequently treated empirically. This study aimed to describe what diagnostic evaluation and therapeutic interventions patients referred for post-bariatric surgery hypoglycemia undergo.

METHODS

Retrospective observational cohort study of patients with a history of bariatric surgery was evaluated for post-bariatric surgery hypoglycemia in a tertiary referral center from 2008 to 2017. We collected demographic and bariatric surgery information, clinical presentation of symptoms referred to as hypoglycemia, laboratory and imaging studies performed to evaluate these symptoms, and symptom management and outcomes.

RESULTS

A total of 60/2450 (2.4%) patients who underwent bariatric surgery were evaluated in the Department of Endocrinology for hypoglycemia-related symptoms. The majority were middle-aged women without type 2 diabetes who had undergone Roux-en-Y gastric bypass. Thirty-nine patients (65%) completed a biochemical assessment for hypoglycemia episodes. Six (10%) had confirmed hypoglycemia by Whipple's triad, and four (6.7%) met the criteria for post-bariatric surgery hypoglycemia based on clinical and biochemical criteria. All patients were recommended dietary modification as the initial line of treatment, and this intervention resulted in most patients reporting at least some improvement in their symptoms. Eight patients (13%) were prescribed pharmacotherapy, and two patients required additional interventions for symptom control.

CONCLUSIONS

In our experience, evaluation for hypoglycemia-related symptoms after bariatric surgery was rare. Hypoglycemia was confirmed in the minority of patients. Even without establishing a diagnosis of hypoglycemia, dietary changes were a helpful strategy for symptom management for most patients.

Metastatic insulinoma presenting with post-prandial hypoglycemia

Background/Objective

Patients with an insulinoma, a type of pancreatic neuroendocrine tumor, typically present with fasting hypoglycemia but can rarely present exclusively with postprandial hypoglycemia.

Case Report

A 69-year-old man presented with episodes of postprandial blurry vision, sweating, and confusion for the last 2 years that were becoming more frequent over the last several weeks. Home blood glucose measurements revealed postprandial hypoglycemia (glucose level, 45-70 mg/dL), and symptoms were consistent with the Whipple triad. Continuous glucose monitoring revealed only postprandial hypoglycemia within 2 hours following meals. An outpatient fast was conducted with detectable insulin (6 μIU/mL) and C-peptide (2.0 ng/mL) levels with an elevated proinsulin (20.8 pmol/L) level when the serum blood glucose level dropped to 47 mg/dL (21 hours after the initiation of the fast). A computed tomography scan of the abdomen and pelvis showed a 1.6-cm hyperenhancing lesion in the distal body of the pancreas. He underwent endoscopic ultrasonography with fine-needle aspiration. Pathology revealed a low-grade, well-differentiated, neuroendocrine tumor with lymphovascular invasion and regional lymph node metastases, confirming the diagnosis of a pancreatic neuroendocrine tumor.

Discussion

Exclusive postprandial hypoglycemia is estimated to occur in 6% of the insulinomas. Patients with postprandial hypoglycemia may be initially managed as those with reactive hypoglycemia; however, this case highlights the importance of evaluating for an insulinoma in a patient who has failed treatment for reactive hypoglycemia. This case also demonstrates the importance of including proinsulin levels in that evaluation.

Conclusion

Pancreatic neuroendocrine tumor should be considered in postprandial hypoglycemia, even in the absence of fasting hypoglycemia. Measuring proinsulin levels is essential in the diagnostic workup of insulinoma causing hypoglycemia.

Metastatic insulinoma presenting after bariatric surgery in a patient diagnosed with MEN1

Insulinomas are uncommon neuroendocrine tumors and metastatic disease is extremely rare. We report a patient with metastatic insulinoma associated with multiple endocrine neoplasia type 1 presenting with hypoglycemia following sleeve gastrectomy. Potential causes of hypoglycemia include dumping syndrome, noninsulinoma pancreatogenous hypoglycemia syndrome, and rarely insulinoma. MEN1‐associated insulinomas have a higher recurrence rate.

The optimal diagnostic criteria of endogenous hyperinsulinemic hypoglycemia based on a large cohort of Chinese patients

PURPOSE

An end-of-fast insulin level ≥ 3 µIU/ml, C-peptide level ≥ 0.6 ng/ml, and proinsulin level ≥ 5 pmol/l with end-of-fast glucose level ≤ 3.0 mmol/l have been established as the criteria for endogenous hyperinsulinemic hypoglycemia. However, all these criteria have been proposed based on patients in Western populations. This study aimed to determine the optimal criteria using a large series of Chinese patients.

METHODS

This retrospective study comprised 144 patients with surgically proven insulinoma and 40 controls who underwent a 72-h fasting test at the Peking Union Medical College Hospital(PUMCH) from 2000 to 2020. Receiver operating characteristic curves were used for analysis.

RESULTS

In this series of patients, the optimal diagnostic criteria for endogenous hyperinsulinemic hypoglycemia were insulin  ≥ 5.5 μIU/ml, C-peptide ≥ 0.7 ng/ml, and proinsulin ≥ 12 pmol/l with end-of-fast glucose ≤ 2.8 mmol/l; the sensitivity and specificity were 99% and 100% for insulin, 100% and 100% for C-peptide, and 93% and 100% for proinsulin, respectively. The diagnostic efficacy of the criteria based on Western populations was then tested. The sensitivity and specificity of end-of-fast insulin ≥ 3 μIU/ml, C-peptide ≥ 0.6 ng/ml, and proinsulin ≥ 5 pmol/l with end-of-fast glucose ≤ 3.0 mmol/l were 100% and 83%, 100% and 80%, and 97% and 78%, respectively.

CONCLUSIONS

New and optimized diagnostic criteria for endogenous hyperinsulinemic hypoglycemia in Chinese populations have been proposed, and these criteria yield satisfactory accuracy.

Using the Secretion Ratios of Insulin and C-peptide During the 2-h Oral Glucose Tolerance Test to Diagnose Insulinoma

BACKGROUND

Insulinoma, owing to the low incidence and small volume of the tumor, is often undiagnosed. The 72-h fast test is centered on diagnosing insulinoma; however, it cannot be performed on outpatients. Our aim was to evaluate the results of a 3-h oral glucose tolerance test (3-h OGTT) for insulinoma diagnosis.

METHODS

Thirty-seven patients with insulinoma were enrolled for comparison with 42 control subjects. All patients underwent 3-h OGTT with measurements of insulin and C-peptide. The secretion ratios of insulin and C-peptide at 1, 2, and 3 h were calculated by comparison with their values at 0 h. We used logistic regression analysis to establish the predictive models and compared the diagnostic efficiency by receiver operating characteristic analysis.

RESULTS

The fasting insulin and C-peptide levels of insulinoma patients were both higher; however, the concentrations at 1 h and 2 h were both lower (P < 0.05). The levels at 3 h were not significantly different (P > 0.05). Our final logistic regression model was constructed as follows: logit (P) = 8.305 - 0.441 × insulin 2 h/0 h ratio - 1.679 × C-peptide 1 h/0 h ratio. A cutoff value of > 0.351 showed the highest diagnostic accuracy, with an area under the curve of 0.97, a sensitivity of 86.5%, and a specificity of 95.2%.

CONCLUSIONS

The 2-h/0-h insulin ratio, as well as the 1-h/0-h C-peptide ratio, has high diagnostic efficiency for insulinoma. The 2-h OGTT can be an alternative test for diagnosing insulinoma in outpatient settings.

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.

Biochemical and Clinical Features of Insulinoma in a Patient with Turner Syndrome

Turner syndrome (TS), i.e., mosaic or nonmosaic states with only one normal X chromosome in females, is characterized by a wide spectrum of somatic, hormonal, and metabolic features. Here we report an unusual case of recurrent hypoglycemia in a 53-year-old woman with TS. Biochemical work-up following a 72h fast revealed detectable, inappropriate for low glucose insulin levels and elevated proinsulin and beta-hydroxybutyrate (BOHB) levels. MR and multiphase CT showed a solid 2.5 cm pancreatic tail mass with absent uptake in the ¹¹¹In-pentetreotide (Octreoscan) scan. Subsequent hepatic vein blood sampling after intra-arterial calcium stimulation showed sharp increase in insulin and modest increase in proinsulin levels. The patient underwent excision of the mass with resolution of symptoms. Histopathologic examination confirmed the neuroendocrine etiology of the tumor. This is, to our knowledge, the third report of TS and concomitant insulinoma. Impaired counterregulatory response to hypoglycemia in patients with TS may result in symptomatic hypoglycemia with only mild insulin elevation and elevated proinsulin in setting of hypoglycemia may be the only indication of insulinoma in these patients. BOHB levels should not be used for ruling out EHH in patients with TS.

Hypoglycaemia without diabetes encountered by emergency medical services: a retrospective cohort study

BACKGROUND

The current study investigates the incidence, aetiology, and outcome of hypoglycaemia of patients without diabetes in the EMS.

METHODS

The study was a retrospective cohort study that utilized electronic EMS patient record system (population of one million). All patients encountered by EMS with plasma glucose ≤3.9 mmol/l from 2009 to 2015 were included in the study and hospital records were screened manually to detect possible reasons for hypoglycaemia. Data from the governmental health insurance agency for all residents in Finland was used to reveal the diabetes status of the patients. Survival of the patients was followed from Population register centre up to six years. Serious hypoglycaemia was defined as plasma glucose ≤3.0 mmol/l.

RESULTS

From EMS cases with a plasma glucose measurement a total of 5467 hypoglycaemic patients without diabetes were encountered by EMS during the study period with an incidence of 1082 (CI95% 1019-1148) per 100,000 inhabitants per year, corresponding 41.6%, (CI95% 40.8-42.3) of all hypoglycaemic patients. Of those patients, 3856 [71.6%, (CI95% 70.4-72.8)] were transported to hospital and 910 [23.2%, (CI95% 22.0-24.6)] had serious hypoglycaemia. The three main diagnosis groups that appeared in the subsequent hospital treatment associated with hypoglycaemia in all transported cases without diabetes as well with serious hypoglycaemia cases were: alcohol abuse [41.2%, (CI95% 39.7-42.8) and 42.2%, (CI95% 39.0-45.4)], hypothermia [17.2%, (CI95% 16.0-18.4) and 27.4%, (CI95% 24.6-30.4)], and malnutrition [16.9%, (CI95% 15.8-18.1) and 25.1%, (CI95% 22.4-28.0)]. Mortality ranged from 0.6-65.4% depending of admission reason and increased significantly at long-term. Non-Diabetics survival was less than with diabetics, when serious hypoglycaemia was present.

DISCUSSION

The most common possible hypoglycaemia related aetiological causes encountered in the EMS, alcohol abuse, hypothermia, and malnutrition, although frequent are often relatively benign conditions. These possible causes of hypoglycaemia can often be treated at scene or need only short hospital admissions. Hence they are not so prevalent in hospital studies.

CONCLUSIONS

Hypoglycaemia without diabetes is commonly observed among the hypoglycaemic EMS cases. Main causes for it are alcohol abuse, hypothermia, and malnutrition. Mortality correlated with age, higher priority dispatch codes, and plasma glucose rate in multivariate logistic regression analysis. Some of the etiological subgroups carry a markedly high mortality rate.

"Riding High on Low Fuel" - Our Experience with Endogenous Hyperinsulinemic Hypoglycemia

INTRODUCTION

Endogenous hyperinsulinemic hypoglycemia (EHH) is a condition in which the insulin levels are inappropriately high in the presence of low plasma glucose.

MATERIALS AND METHODS

We did a retrospective analysis of case records of those patients admitted and evaluated for EHH from June 2004 to June 2016 in our center, excluding those that were diagnosed with reactive hypoglycemia. We collected data regarding demographics, clinical presentation, laboratory results, localization techniques, and treatment administered.

RESULTS

Sixteen patients who were admitted for evaluation based on history suggestive of repeated hypoglycemic episodes were included in the study. All but one pregnant patient was subjected to a supervised fast in the hospital. All patients developed hypoglycemia (defined using Whipple's triad) within the first 24 h. Three patients had autoimmune hypoglycemia which differed significantly from insulinoma-mediated hypoglycemia in certain clinical and laboratory parameters. They were older in age with marked fluctuations in the 24 h glucose profile ranging from frank hypoglycemia to frank hyperglycemia. The insulin levels were markedly elevated in this group of patients along with a significantly elevated insulin C peptide molar ratio (ICMR) when compared with patients with insulinoma-mediated hypoglycemia.

CONCLUSIONS

Although insulinoma is the most common cause of EHH, autoimmune hypoglycemia should be considered as a differential diagnosis, particularly in older individuals with plasma glucose values increasing to the hyperglycemic range. Degree of elevation of insulin levels and ICMR may provide additional clues. Overall, the survival and prognosis of patients with EHH are excellent.

MANAGEMENT OF ENDOCRINE DISEASE: Pathogenesis and management of hypoglycemia

Glucose is the main substrate utilized by the brain and as such multiple regulatory mechanisms exist to maintain glucose concentrations. When these mechanisms fail or are defective, hypoglycemia ensues. Due to these robust mechanisms, hypoglycemia is uncommon and usually occurs in the setting of the treatment of diabetes using glucose-lowering agents such as sulfonylureas or insulin. The symptoms of hypoglycemia are non-specific and as such it is important to confirm hypoglycemia by establishing the presence of Whipple's triad before embarking on an evaluation for hypoglycemia. When possible, evaluation of hypoglycemia should be carried out at the time of spontaneous occurrence of symptoms. If this is not possible then one would want to create the circumstances under which symptoms occur. In cases where symptoms occur in the post absorptive state, a 72-h fast should be performed. Likewise, if symptoms occur after a meal then a mixed meal study may be the test of choice. The causes of endogenous hyperinsulinemic hypoglycemia include insulinoma, post-bariatric hypoglycemia and noninsulinoma pancreatogenous hypoglycemia syndrome. Autoimmune hypoglycemia syndrome is clinically and biochemically similar to insulinoma but associated with high levels of insulin antibodies and plasma insulin. Other important causes of hypoglycemia include medications, non-islet cell tumors, hormonal deficiencies, critical illness and factitious hypoglycemia. We provide an overview of the pathogenesis and management of hypoglycemia in these situations.

ANTHROPOMETRIC FEATURES ARE NOT PREDICTIVE OF 72-HOUR FAST DURATION IN INSULINOMAS

OBJECTIVE

The 72-hour fast is used to document Whipple's triad and understand the mechanism of hypoglycemia. Although hypoglycemia develops within 24 hours in the majority of fasts, identifying possible determinants of fast duration may help to predict the need for admission. Therefore, we determined the relation between anthropometric features on fast duration and assessed end of fast parameters on maximal tumor size, extent of disease, or tumor recurrence.

METHODS

A retrospective analysis of patients with insulinoma in the past 25 years who underwent a 72-hour fast was conducted. Electronic medical records were reviewed to obtain anthropometric patient data and tumor characteristics.

RESULTS

A total of 233 patients underwent the 72-hour fast. The mean age at diagnosis was 50 ± 16 years, with a body mass index (BMI) of 29 ± 7 kg/m², and 66% (153 of 233) were female. Duration of fast was not associated with gender (P = .2), age (P = .3), or BMI (P = .7). A shorter fast duration was inversely related to end of fast C-peptide (P = .0075) but not insulin (P = .13) or proinsulin (P = .28) concentration. End of fast C-peptide was associated with increased tumor size (P = .036) and multiplicity (P =.01). Proinsulin was associated with increased tumor size (P<.01) and malignancy (P = .018).

CONCLUSION

Duration of fast was not significantly related age, gender, weight, or BMI, although end-of-fast C-peptide and proinsulin may provide some information regarding tumor characteristics. Consequently, the duration of fast cannot be predicted a priori and should be allowed to run for the planned length unless hypoglycemia develops. Abbreviation: BMI = body mass index.

Endoscopic ultrasound-guided fine-needle aspiration biopsy (EUS-FNA) in insulinomas: Indications and clinical relevance in a single investigator cohort of 47 patients

PURPOSE

This study was aimed to investigate the role and relevance of endoscopic ultrasound-guided fine-needle aspiration biopsy in the diagnostic work-up of insulinomas.

METHODS

We have analysed the frequency, clinical indications, success rate (obtaining diagnostic tissue), diagnostic accuracy (in comparison to the pathological diagnosis after surgery), complications, and tolerability of endoscopic ultrasound-guided fine-needle aspiration biopsy and the localization and size of the lesions in 47 consecutive patients (29 females, 18 males; 46 ± 15 years) who had surgery for insulinoma following fasting test and were explored by single investigator EUS 1994-2015.

RESULTS

Endoscopic ultrasound-guided fine-needle aspiration biopsy was performed in 21 % (10/47) of the patients. The clinical indications for endoscopic ultrasound-guided fine-needle aspiration biopsy were non-conclusive result of fasting test (n = 7), missing toxicology (n = 2), suspected malignancy at EUS (n = 1), suspicious extra-pancreatic localization of the lesion (n = 1). The diagnostic success rate of the procedure was 80 % (8/10 cases), the diagnostic accuracy of the fine-needle aspiration biopsy 70 % (7/10 cases). The lesions undergoing endoscopic ultrasound-guided fine-needle aspiration biopsy were localized in the cauda (n = 5), corpus (n = 2), caput/processus uncinatus (n = 3), the diameter of the tumors was 21 ± 18 (10-70) mm. Only one accidental vascular puncture without any clinical complication occurred and all patients tolerated the procedure well.

CONCLUSIONS

In the majority of cases, positive fasting test, negative toxicology, and detection of a typical pancreatic lesion at endoscopic ultrasound is sufficient for the diagnosis of insulinoma and the definition of the appropriate surgical strategy. Based on our data, we suggest including endoscopic ultrasound-guided fine-needle aspiration biopsy in the diagnostic work-up of organic hyperinsulinism in selected patients with inconclusive or uncertain diagnosis before surgery.

Complicated Case Presentation: Management of Pancreatic Neuroendocrine Tumors in Multiple Endocrine Neoplasia Type 1

Multiple endocrine neoplasia type 1 (MEN1) is an inherited predisposition to tumors of the parathyroid glands, anterior pituitary, and pancreatic islet cells. In this review, we discuss the clinical case of a 45-year-old woman with MEN1 that was presented at the 2015 North American Neuroendocrine Tumor Society Symposium. In our review of this patient's complicated clinical course and subsequent operative management, we highlight controversies in the diagnosis and management of pancreatic neuroendocrine tumors in MEN1. In particular, this case illustrates the lack of consensus regarding the optimal biochemical and radiologic screening for pancreatic neuroendocrine tumors and absence of guidelines about the appropriate surgical approach for treatment. We review these controversies and discuss possible approaches to management.

Biomarkers of Insulin for the Diagnosis of Hyperinsulinemic Hypoglycemia in Infants and Children

OBJECTIVE

To evaluate thresholds of various biomarkers for defining excess insulin activity to recognize congenital hyperinsulinism.

STUDY DESIGN

This was a retrospective chart review of diagnostic fasting tests in children with ketotic hypoglycemia (n = 30) and genetically/pathology confirmed congenital hyperinsulinism (n = 28). Sensitivity and specificity for congenital hyperinsulinism were determined for plasma insulin, β-hydroxybutyrate, free fatty acids (FFA), C-peptide, insulin-like growth factor binding protein-1 (IGFBP-1), and the glycemic response to glucagon (through the glucagon stimulation test [GST]) at the time of hypoglycemia.

RESULTS

Only 23 of the 28 subjects with congenital hyperinsulinism had detectable insulin (median, 6.7 μIU/mL), and insulin was undetectable in all subjects with ketotic hypoglycemia. Compared with ketotic hypoglycemia, subjects with congenital hyperinsulinism had higher GST values (57 vs 13 mg/dL; ΔGST ≥30 mg/dL in 24 of 27 subjects with congenital hyperinsulinism vs 0 of 30 subjects with ketotic hypoglycemia) and C-peptide levels (1.55 vs 0.11 ng/mL), with lower levels of FFA (0.82 vs 2.51 mM) and IGFBP-1 (59.5 vs 634 ng/mL). At the time of hypoglycemia, the upper limits of β-hydroxybutyrate and FFA in subjects with congenital hyperinsulinism were higher than reported previously (β-hydroxybutyrate <1.8 mM and FFA <1.7 mM), providing the best sensitivity for congenital hyperinsulinism vs ketotic hypoglycemia. A C-peptide level ≥0.5 ng/mL was 89% sensitive and 100% specific, and an IGFBP-1 level ≤110 ng/mL was 85% sensitive and 96.6% specific.

CONCLUSION

Because low or undetectable insulin level during hypoglycemia does not exclude the diagnosis of hyperinsulinism, C-peptide and IGFBP-1 may inform the diagnosis of congenital hyperinsulinism. In this group of children with well-defined congenital hyperinsulinism, thresholds for "suppressed" β-hydroxybutyrate and FFA are higher than previously reported levels.

Clinical features and causes of endogenous hyperinsulinemic hypoglycemia in Korea

BACKGROUND

Endogenous hyperinsulinemic hypoglycemia (EHH) is characterized by an inappropriately high plasma insulin level, despite a low plasma glucose level. Most of the EHH cases are caused by insulinoma, whereas nesidioblastosis and insulin autoimmune syndrome (IAS) are relatively rare.

METHODS

To evaluate the relative frequencies of various causes of EHH in Korea, we retrospectively analyzed 84 patients who were diagnosed with EHH from 1998 to 2012 in a university hospital.

RESULTS

Among the 84 EHH patients, 74 patients (88%), five (6%), and five (6%) were diagnosed with insulinoma, nesidioblastosis or IAS, respectively. The most common clinical manifestation of EHH was neuroglycopenic symptoms. Symptom duration before diagnosis was 14.5 months (range, 1 to 120 months) for insulinoma, 1.0 months (range, 6 days to 7 months) for nesidioblastosis, and 2.0 months (range, 1 to 12 months) for IAS. One patient, who was diagnosed with nesidioblastosis in 2006, underwent distal pancreatectomy but was later determined to be positive for insulin autoantibodies. Except for one patient who was diagnosed in 2007, the remaining three patients with nesidioblastosis demonstrated severe hyperinsulinemia (157 to 2,719 µIU/mL), which suggests that these patients might have had IAS, rather than nesidioblastosis.

CONCLUSION

The results of this study suggest that the prevalence of IAS may be higher in Korea than previously thought. Therefore, measurement of insulin autoantibody levels is warranted for EHH patients, especially in patients with very high plasma insulin levels.

Approach to the patient with spontaneous hypoglycemia

Hypoglycemia is common in daily clinical practice and often occurs during the treatment of diabetes mellitus. However, a small minority of hypoglycemia encountered in clinical practice is spontaneous and thus not induced by glycemic lowering agents. These spontaneous hypoglycemic events confront the clinician with a diagnostic enigma. Although the trained clinician can recognize the autonomic and neuroglycopenic symptoms of hypoglycemia even in a patient not on insulin, it remains challenging to decipher the etiology of a spontaneous hypoglycemic event. A logical and stepwise approach to the spontaneous hypoglycemic event allows for a conclusive diagnosis. This diagnostic process consists of adequately diagnosing hypoglycemia by fulfilling Whipple's triad, stratifying patients according to their clinical status and analyzing a full hypoglycemic blood panel. A complete hypoglycemic blood panel should include the analysis of glucose, insulin, C-peptide, pro-insulin, insulin antibodies and the presence of oral hypoglycemic agents. For patients with episodes of hypoglycemia induced by excessive endogenous insulin, additional imaging is often required to detect the presence of an underlying insulinoma. By diagnosing the underlying cause of the spontaneous hypoglycemia, the physician also diagnosis the mechanism by which the hypoglycemic event occurs. Allowing for a problem orientated therapeutic approach.

METHODOLOGY

The present review is based upon a comprehensive PubMed search between 1985 and 2013. This uses search terms of spontaneous hypoglycemia, insulinoma, nesidioblastosis, insulin auto-immunity, noninsulinoma pancreatogenous hypoglycemia syndrome, hormone deficiency, pro-IGF II, and pro-insulin growth factor II, and cross reference searching of pivotal articles in the subject.

Insulinoma: only in adults?-case reports and literature review

Insulinomas first presenting as refractory seizure disorders are well documented in adulthood but rarely found in children. Only a few cases of childhood insulinoma have been reported so far. We report on two adolescents with hyperinsulinaemic hypoglycaemia, initially misdiagnosed as epilepsy and migraine accompagnée, and compare those to other cases published. Localization of insulinoma was challenging and, in one patient, angiography with selective arterial calcium stimulation and hepatic venous sampling in addition to CT and MRI was necessary. In these patients, long-term recovery was achieved by laparoscopic distal pancreatic resection in one and by conventional enucleation in the pancreatic head in the second patient. In contrast to adults, macrosomy and a decrease in school performance were the main symptoms and, during fasting, impaired cognitive function occurred after a relatively short period and at a higher glucose threshold or lower insulin/glucose ratio, respectively. Neuroglycopenic signs may be attributed to behaviour abnormalities or seizure disorders but in children and adolescents may already be caused by insulinoma. In these cases, timely diagnosis as well as tumour resection ensure long-term cure.

An insulinoma presenting with hypochondriac delusions and food refusal

The authors report a case of a 68-year-old man with an unrecognized insulinoma manifesting with neuropsychiatric symptoms. For two years, he presented with unspecified behavior changes, autonomic and neuroglycopenic symptoms, which led him to be misdiagnosed with a neurologic and psychiatric disorder before the insulinoma was recognized. Following neurological alterations in context of hypoglycemia, subsequent to longstanding food refusal, he was admitted in the psychiatric ward. Despite good global response and normal food intake, hypoglycemic episodes were still occurring and led to a careful evaluation which permitted the definitive diagnostic. This case highlights the diagnostic difficulties of medical disorders presenting with clinical features overlapping neurological and psychiatric syndromes. It also reflects the diagnostic difficulties in rare clinical entities, particularly in patients previously followed in psychiatry and underlines the need for a constant dialogue and updating of clinicians.

Presentation, diagnostic features and glucose handling in a monocentric series of insulinomas

BACKGROUND

New aspects have emerged in the clinical and diagnostic scenarios of insulinoma: current guidelines have lowered the diagnostic insulin threshold to 3 μU/ml in the presence of hypoglycemia (<55 mg/dl); post-prandial hypoglycemia has been reported as the only presenting symptom; preexisting diabetes mellitus (DM) was recognized in some patients.

AIM

To evaluate clinical features, diagnostic criteria and glucose metabolic profile in a monocentric series of patients affected by insulinomas including two subgroups: sporadic and multiple endocrine neoplasia type-1 syndrome (MEN-1).

SUBJECTS AND METHODS

Clinical, pathological and biochemical data regarding 33 patients were analyzed.

RESULTS

following the current guidelines the 72-h fasting test was initially positive in all cases but one. In this case the test, initially negative, became positive after a 2-yr follow-up. Nadir insulin level was ≥ 3 μU/ml but <6 μU/ml in 3 patients and ≥ 6 μU/ml in the remaining 30 cases. At presentation, 27 patients (82%) reported only fasting symptoms, 3 (9%) only post-prandial and 3 (9%) both. Seven cases (21%) had previously been affected by type 2 DM or impaired glucose metabolism.

CONCLUSIONS

In our series the new cut-off of insulin increased the sensitivity of the 72-h fasting test from 87% to 97%. The absence of hypoglycemia during the test cannot definitively rule out the diagnosis and the test should be repeated in every highly suspicious case. Post-prandial hypoglycemia can be the only presenting symptom. DM may be associated with the occurrence of insulinoma. So that a possible diagnosis of insulinoma must not be ignored if previous impaired glucose handling is evident.

Increased plasma β-hydroxybutyrate levels during the fasting test in patients with endogenous hyperinsulinaemic hypoglycaemia

OBJECTIVE

The objective of the present study was to determine whether a plasma β-hydroxybutyrate (BOHB) level >2700 μmol/l during the 72-h fasting test is sufficient to rule out the diagnosis of endogenous hyperinsulinaemic hypoglycaemia (EHH).

RESEARCH DESIGN AND METHODS

We retrospectively studied BOHB levels in 39 patients with EHH who had undergone a 72-H fasting test to make the diagnosis of EHH, and we compared EHH patients with BOHB levels 2700 MOL/L (group 1), EHH PATIENTS with BOHB levels 2700 MOL/L (group 2) and 59 controls (median glycaemia: 3.2  mmol/l and median BOHB: 6095 μmol/l).

RESULTS

During a 72-h fasting test, nine patients (group 1) had BOHB levels >2700  μmol/l (median 6140 and range 2957-7824) and 30 patients (group 2) had BOHB levels <2700 μmol/l (median 542 and range 0-2607). In group 1, four patients had undergone partial pancreatectomy previously and were evaluated for the recurrence of hypoglycaemia, whereas none of the group 2 patients had been operated. The duration of the fasting test was longer in group 1 than in group 2 (P<0.0001), and at the end of the fasting test, plasma glucose concentrations were not significantly different (P=0.0617), but insulin (P=0.004), C-peptide (P=0.0015) and proinsulin (P=0.0038) levels were significantly lower in group 1 patients than in group 2 patients, suggesting lower insulin secretion and/or impaired glycaemic counter-regulation.

CONCLUSION

During a fasting test, a BOHB level >2700 μmol/l is observed in some EHH patients, suggesting that BOHB levels cannot rule out the recurrence of EHH, in particular, after partial pancreatectomy.

Persistent Hypoglycemia of Unknown Etiology in a Patient Without Diabetes

Purpose: This case report reviews the presentation, evaluation, and treatment of persistent hypoglycemia in a patient without a history of diabetes. The use of laboratory tests to differentiate between drug-induced and disease-induced hypoglycemia is reviewed. Summary: A 51-year-old female with multiple medical conditions including bipolar disorder and no history of diabetes was admitted for evaluation and treatment of hypoglycemia. Pharmacotherapy included intravenous dextrose infusions and bolus doses. A battery of tests was ordered to evaluate intrinsic and extrinsic causes. Endocrine Society guidelines for hypoglycemia exist and have recommendations for testing and strategies to rule out drug-related causes. Her insulin level was 57 IU/mL (normal range < 17). Her proinsulin level was 356.8 pmol/L (normal range <8.8). Conclusion: The guidelines recommend a battery of laboratory tests; however, the results are not rapidly available necessitating a structured follow-up process. In our patient, exposure to hypoglycemic agents and exogenous insulin can be ruled out. Autoimmune hypoglycemia or a hypoglycemic reaction to one of her home medications is very unlikely, but cannot be ruled out. An insulinoma is the most likely etiology of her hypoglycemia, but that cannot be confirmed.

A case of malignant insulinoma: successful control of glycemic fluctuation by replacing octreotide injections with octreotide LAR injections

A 73-year-old woman with malignant insulinoma was treated with 100 μg/day octreotide for unresected insulinoma and liver metastases. The daily administration of the drug induced hyperglycemia after dinner in addition to existing fasting hypoglycemia possibly because this drug suppressed both insulin and glucagon secretion and its blood concentration was unstable. After replacing a daily injection of octreotide with a monthly injection of octreotide long-acting repeatable (LAR), blood glucose levels stabilized within the normal range. The findings of the present study showed that octreotide LAR could be useful for the long-term treatment of unresectable insulinomas.

[Endogenous hyperinsulinism: review and follow-up of 24 cases]

Hypoglycemia due to endogenous hyperinsulinism (EH) is diagnosed in a symptomatic patient with low levels of plasma glucose concomitant with elevated plasma insulin and C-peptide. Causes of EH are pancreatic islet-cells disease, use of insulin secretagogues, and autoimmune hypoglycemia. In this review, the authors studied 24 patients with hypoglycemia due to endogenous hyperinsulinism in order to describe aspects of diagnosis and treatment. Our study demonstrated that after 12 hours of fasting (mini-fasting test; at least three samples), all patients presented the diagnostic criteria for EH. Additionally, we found that 11 of 12 patients (91.7%) who underwent glucagon test achieved glucose levels less than 50 mg/dL and below baseline after 120 minutes. Mini-fasting (3 samples) and glucagon test may be useful to prevent prolonged fasting test to clarify the diagnosis of endogenous hyperinsulinism.

Paroxysmal dystonic choreoathetosis with symptomatic seizures secondary to hypoglycemia caused by insulinoma

Neurological syndromes are not an uncommon presentation with insulinomas. Recurrent hypoglycemia associated with it can present with a variety of neurological symptoms that may include disturbances of consciousness, seizures, stroke-like presentation, movement disorder, dementia and chronic neuropathy. The myriad of presentations, resemblance with other neurological conditions and episodic nature often lead to misdiagnosis and a delay in definitive treatment. Rare cases of insulinoma presenting as combination of abnormal movements have been described. We report a patient who presented with both hypoglycemia induced symptomatic seizures and paroxysmal non-kinesiogenic dystonic choreoathetosis. Insulinoma is a potentially treatable disorder and early definitive intervention can prevent long term neurological disability in patients.

Diagnosis and localisation of insulinoma: the value of modern magnetic resonance imaging in conjunction with calcium stimulation catheterisation

CONTEXT

Preoperative localisation of insulinoma improves cure rate and reduces complications, but may be challenging.

OBJECTIVE

To review diagnostic features and localisation accuracy for insulinomas.

DESIGN

Cross-sectional, retrospective analysis.

SETTING

A single tertiary referral centre.

PATIENTS

Patients with insulinoma in the years 1990-2009, including sporadic tumours and those in patients with multiple endocrine neoplasia syndromes.

INTERVENTIONS

Patients were identified from a database, and case notes and investigation results were reviewed. Tumour localisation by computed tomography (CT), magnetic resonance imaging (MRI), octreotide scanning, endoscopic ultrasound (EUS) and calcium stimulation was evaluated.

MAIN OUTCOME MEASURE(S)

Insulinoma localisation was compared to histologically confirmed location following surgical excision.

RESULTS

Thirty-seven instances of biochemically and/or histologically proven insulinoma were identified in 36 patients, of which seven were managed medically. Of the 30 treated surgically, 25 had CT (83.3%) and 28 had MRI (90.3%), with successful localisation in 16 (64%) by CT and 21 (75%) by MRI respectively. Considered together, such imaging correctly localised 80% of lesions. Radiolabelled octreotide scanning was positive in 10 out of 20 cases (50%); EUS correctly identified 17 lesions in 26 patients (65.4%). Twenty-seven patients had calcium stimulation testing, of which 6 (22%) did not localise, 17 (63%) were correctly localised, and 4 (15%) gave discordant or confusing results.

CONCLUSIONS

Preoperative localisation of insulinomas remains challenging. A pragmatic combination of CT and especially MRI predicts tumour localisation with high accuracy. Radionuclide imaging and EUS were less helpful but may be valuable in selected cases. Calcium stimulation currently remains useful in providing an additional functional perspective.

Giant malignant insulinoma which developed from a non-functioning pancreatic tumor over a long period of time

Insulinomas are the most common hormone-producing pancreatic neuroendocrine tumors (NETs), which are usually benign, solitary and small. We describe herein a patient with a giant insulinoma (>10 cm in diameter) with concomitant thyroid tumor as detected by Somatostatin receptor scintigraphy (SRS). A 50-year-old man presented hypoglycemic symptoms 20 years after the first detection of a pancreatic tumor, which was ameliorated by administration of a somatostatin analogue, octreotide. SRS showed abnormal uptake by the insulinoma as well as by the thyroid tumor. RT-PCR and immunohistochemical study revealed abundant expression of somatostatin receptor (SSTR)-1, -2, and -5 in his insulinoma and SSTR-1 and -2 in his thyroid follicular neoplasm. This is a rare case of a slow-growing pancreatic well-differentiated neuroendocrine carcinoma over a long period of time to become a symptomatic giant insulinoma. Furthermore, SRS proves to be a useful tool for localization of insulinoma as well as concomitant thyroid neoplasm with predominant expression of SSTRs.

Glucose-responsive insulinoma in a patient with postprandial hypoglycemia in the morning

We report the case of an obese 79-year-old woman who experienced postprandial hypoglycemia in the morning. The serum immunoreactive insulin (IRI) and C-peptide levels responded in parallel with her serum glucose level during a 75-g oral glucose tolerance test. A prolonged fast test lowered her serum glucose level to 30 mg/dL, but serum IRI was not fully suppressed. Abdominal computed tomography revealed a tumor in the uncinate process of the pancreas. The tumor was histologically diagnosed as benign insulinoma after surgery. Therefore, glucose-responsive insulinoma as well as reactive hypoglycemia should be considered in patients who exhibit postprandial hypoglycemia.

Insulinoma

Insulinoma is a rare neuroendocrine tumor with an incidence of 4 per 1 million persons per year, which may occur as a unifocal sporadic event in patients without an inherited syndrome or as a part of multiple endocrine neoplasia type 1. Key neuroglycopenic and hypoglycemic symptoms in conjunction with biochemical proof establish the diagnosis. Once the diagnosis is established, the insulinoma is preoperatively localized within the pancreas with the goal of surgical excision for cure. This review discusses the historical background, diagnosis, and management of sporadic insulinoma.

Secular trends in the presentation and management of functioning insulinoma at the Mayo Clinic, 1987-2007

OBJECTIVE

The objective of the study was to assess changes in the presentation and diagnostic and radiological evaluation of patients with surgically confirmed insulinoma at the Mayo Clinic 1987-2007.

METHODS

A retrospective analysis of patients with insulinoma was conducted. Patients with prior gastric bypass were excluded.

RESULTS

A total of 237 patients [135 women (57%)] were identified. Hypoglycemia was reported solely in the fasting state in 73%, the fasting and postprandial state in 21%, and exclusively postprandially in 6%. There was a predominance of men in the postprandial symptom group. Considering the period of study by quartile, outpatient evaluation increased from 35 to 83% and successful preoperative localization improved from 74 to 100% comparing the first to the fourth quartiles. Although the rates of localization by noninvasive techniques remained static at approximately 75%, the addition of invasive modalities has resulted in successful preoperative localization in all patients in the past 10 yr. The sensitivity and specificity of the established diagnostic criteria using insulin, C-peptide, proinsulin, beta-hydroxybutyrate, and glucose response to iv glucagon were greater than 90% and greater than 70%, respectively.

CONCLUSIONS

Although fasting hypoglycemia is characteristic of patients with insulinoma, postprandial symptoms have been reported with increasing, albeit low, frequency. Trends in the evaluation and preoperative management include a shift to outpatient diagnostic testing, an emphasis on successful preoperative localization to avoid blind pancreatic exploration, and a validation of the diagnostic criteria for hyperinsulinemic hypoglycemia.

Differentiation of insulin secretion patterns in insulinoma

BACKGROUND

In patients with insulinoma, biochemical proof of inappropriately elevated insulin secretion during hypoglycemia is required prior to surgery. Because circulating insulin levels usually vary widely, we have used the combined OGTT-fasting test to define new normative criteria for a retrospective systematic analysis.

METHODS

We retrospectively analyzed insulin concentrations from OGTT-fasting tests of 64 patients with surgically removed insulinomas. In addition, the response to intravenous somatostatin infusions was estimated. Normative criteria were defined to obtain comparable estimates of insulin concentrations: basal, glucose-stimulated maximum, postglucose plateau, and secretory bursts.

RESULTS

Three types of insulin secretion patterns were identified: (1) the autonomous secretion pattern (type 1, N=17) with basal and post-OGTT plateau insulin concentrations of approximately 50 mU/L, suppression after OGTT by 41%, virtual absence of distinctive secretory bursts, and resistance to somatostatin-mediated suppression (25 %); (2) the inadequate suppression pattern (type 2, N=28) with moderately elevated basal and post-OGTT insulin concentrations of approximately 20 mU/L, suppression after OGTT by 73%, absence of secretory bursts, and incomplete somatostatin-induced suppression (56 %); (3) the late-burst secretion pattern (type 3, N=19) with similar basal and post-OGTT insulin concentrations of 17 mU/L, suppression after OGTT by 76%, true insulin bursts of Delta 13+/-11 mU/L (184%), and nearly complete somatostatin-induced suppression by 64%.

CONCLUSIONS

By means of a new normative analysis of the combined OGTT-fasting test, three different patterns of insulin secretion can be described in patients with insulinoma: the autonomous secretion type, the inadequate suppression type, and the late-burst secretion type.

Non-insulinoma persistent hyperinsulinaemic hypoglycaemia caused by an activating glucokinase mutation: hypoglycaemia unawareness and attacks

OBJECTIVE

Adult-onset non-insulinoma persistent hyperinsulinaemic hypoglycaemia (NI-PHH) and the variant NI-pancreatogenous hypoglycaemia syndrome (NIPHS) are genetically unexplained diseases, without reports of hypoglycaemia unawareness or familial inheritance.

DESIGN AND PATIENTS

In a prospective 8-year follow-up, a boy (i) with NI-PHH since age 14 years, his mother (ii), the mother's brother (iii) and his daughter (iv) were studied.

RESULTS

Patient (i) was characterized by especially postprandial hypoglycaemia down to 1.6 mmol/l and pronounced variability in diazoxide need with obesity; (ii) had asymptomatic blood glucose down to 2.9 mmol/l, but a severe hypoglycaemic postprandial attack after a slimming diet; (iii) had moderate hypoglycaemic symptoms since childhood and need of frequent eating; and (iv) was asymptomatic until a hypoglycaemic accident in the age of 24. After a slimming diet, symptomatic fasting, but especially postprandial hypoglycaemia occurred (blood glucose 1.9 mmol/l after 19 h fasting; 1.6 mmol/l 3.5 h after OGTT). By CT-scan/endoscopic ultrasound in three of the individuals, insulinoma could not be detected. In all four individuals, an activating glucokinase (GCK) mutation A456V was found. No mutations were found in the ABCC8 or KCNJ11 genes. The patients responded to treatment with diazoxide or octreotide long acting release.

CONCLUSION

This is the first report to highlight a genetic cause to adult-onset NI-PHH/NIPHS. The activating GCK mutation was dominantly inherited, but only after year-long follow-up and investigations, other family members were diagnosed symptomatic. Hypoglycaemia unawareness seems to be a prominent feature, but hypoglycaemic attacks occur after slimming, especially postprandially. PHH-GCK was medical responsive.

Paraneoplastic hyperinsulinism and secondary hypoglycaemia in a patient with advanced colon cancer: A rare association

We review the case of a 74-year-old patient with advanced colon cancer who suffered recurrent bouts of hypoglycemia. A state of inappropriate, non-suppressed hyperinsulinism in the presence of severe hypoglycemia was diagnosed. We finally discuss the known mechanisms behind fasting hypoglycemia in patients with advanced cancer, the diagnosis, and possible treatments of this rare paraneoplastic endocrine complication.

Sporadically occurring functional pancreatic endocrine tumors: review of recent literature

PURPOSE OF REVIEW

Pancreatic neuroendocrine tumors are rare neoplasms often associated with a clinical syndrome. Their rarity makes a comprehensive study difficult at any single institution, while their uniqueness makes them desirable for investigation. This review summarizes recent information and advancements concerning pancreatic neuroendocrine tumor diagnosis, imaging characteristics, treatment algorithms, and staging.

RECENT FINDINGS

Insulinomas and gastrinomas comprise the majority of functional pancreatic neuroendocrine tumors. Advances in their identification and diagnostic evaluation, imaging techniques, and treatment algorithms are presented. Furthermore, a new staging classification system has been proposed which may significantly improve the ability to conduct future multi-institutional investigations on pancreatic neuroendocrine tumors.

SUMMARY

Although rare, a thorough understanding of pancreatic neuroendocrine tumors is essential for all physicians due to the wide variety of symptoms with which patients present. Currently, patients are often misdiagnosed for extended periods of time. This review summarizes the recently published literature about diagnosis, imaging, treatment, and staging of pancreatic neuroendocrine tumors.

Insulin & C-peptide levels in sulfonylurea-induced hypoglycemia: a systematic review

OBJECTIVES

We will describe insulin and C-peptide levels observed in sulfonylurea-induced hypoglycemia and determine whether these levels differed if obtained before or after hypoglycemic therapy.

METHODS

We performed a systematic review of the English literature to identify Medline articles containing "sets" (glucose <60 mg/dL with insulin and C-peptide levels). These "sets" were categorized as being obtained BEFORE, AFTER, or UNKNOWN with respect to hypoglycemic therapy.

RESULTS

22 articles, 76 patients, and 97 "sets" were included. Mean glucose (mg/dL), insulin (muIU/mL), and C-peptide (ng/mL) for all "sets' were 28.6 (+/-12.6; 26.1 to 31.2), 54.4 (+/-126.3; 28.3 to 80.5), 7.2 (+/-6.2; 5.9 to 8.5). The BEFORE measures were 24.3 (+/-7.3; 18.7 to 30.0), 36.6 (+/-26.2; 16.5 to 56.7), 5.4 (+/-4.6; 1.5 to 9.2). The AFTER measures were 33.1 (+/-9.8; 28.2 to 38.0), 126.7 (+/-278.1; 0 to 265.0), 10.3 (+/-10.5; 5.1 to 15.4). The UNKNOWN measures were 28.0 (+/-13.5; 24.7 to 31.3), 37.1 (+/-21.8; 31.7 to 42.5), 6.5 (+/-4.3; 5.4 to 7.6). Only one "set" (glucose 49 mg/dL) had insulin <3.9 muIU/mL and C-peptide <1.4 ng/mL.

CONCLUSIONS

Insulin > or =3.9 muIU/mL, C-peptide > or =1.4 ng/mL, and glucose <49 mg/dl are consistent with sulfonylurea-induced hypoglycemia. BEFORE levels were lower, but they were consistent with sulfonylurea-induced hypoglycemia.

Preoperative diagnosis of insulinoma: low body mass index, young age, and female gender are associated with negative imaging by endoscopic ultrasound

OBJECTIVE

Endoscopic ultrasound (EUS) is a highly reliable procedure to localize insulinomas preoperatively. It has been considered to be important in planning surgical strategy, especially considering a minimal invasive approach. However, even under ideal conditions experienced examiners miss about 10-20% of insulinomas by EUS imaging.

DESIGN AND METHODS

This retrospective study aimed to identify factors associated with negative EUS imaging. Twenty-nine consecutive patients (24 benign and 5 malignant) with sporadic pancreatic insulinomas confirmed by successful surgery and positive histopathology were included. All EUS examinations were performed by one single experienced examiner over a period of one decade.

RESULTS

Three of the tumors were not detected by preoperative EUS as they were isoechoic to the surrounding healthy pancreatic tissue; 25 could be detected as hypoechoic lesions, (including all malignant tumors), and one lesion was hyperechoic. Low body mass index (P=0.053) and young age (P=0.037) were associated with negative EUS imaging. All patients with negative imaging were females. The position on the examiner's learning curve, the diameter and location of insulinoma, and endocrine parameters (insulin concentrations and insulin-glucose ratios in the prolonged fasting test) had no influence on the success of EUS imaging.

CONCLUSIONS

Some insulinomas are missed by preoperative EUS imaging as they are completely isoechoic. A low body mass index, female gender, and young age might be risk factors for negative imaging.

Hypoglycemia due to an insulin binding antibody in a patient with an IgA-kappa myeloma

CONTEXT

Autoantibodies to insulin have been described to cause spontaneous hypoglycemia in nondiabetic subjects. There have been occasional reports of spontaneous hypoglycemia due to monoclonal anti-insulin antibodies. We present the first report of a patient with an IgA-kappa myeloma in whom frequent hypoglycemia resulted from the ability of the monoclonal IgA-kappa to bind insulin.

OBJECTIVES

The aim of this study was to describe the occurrence of profound hypoglycemia in a patient with IgA-kappa myeloma, characterize biochemically the nature of the IgA:insulin complex present, and place this case in the context of the published literature on hypoglycemia resulting from autoantibodies to insulin.

DESIGN

A case study was performed.

PATIENTS

A single case of profound hypoglycemia associated with IgA-kappa myeloma was studied.

INTERVENTION

There were no interventions.

MAIN OUTCOME MEASURES

A case study was performed.

RESULTS

Polyethylene glycol precipitation and gel filtration chromatography were used to demonstrate high-molecular weight insulin immunoreactivity in the patient's plasma. This was characterized as an insulin binding IgA-kappa paraprotein present at 4200 mg/dl (42 g/liter) with a relatively high insulin dissociation constant of 0.32 microm/liter using radiolabelled insulin binding studies.

CONCLUSIONS

We present the first case of hypoglycemia due to IgA binding insulin antibodies in a patient with an IgA-kappa paraprotein myeloma. The hypoglycemia was associated with high-plasma insulin levels and relatively low C-peptide levels. A plausible mechanism for the hypoglycemia is the delayed clearance of insulin. This case broadens the spectrum of monoclonal gammopathies that have been associated with anti-insulin reactivity and spontaneous hypoglycemia.

Localisation and surgical treatment of insulinomas

Most insulinomas are solitary, benign and functional neuroendocrine pancreatic tumours which give rise to manifold symptoms. Their preoperative localisation is often unclear, but the cure rate after their excision is very high. It was the aim of this study to analyse and evaluate our group of patients with regard to preoperative tumour localisation and overall surgical results. Twelve patients with a biochemical diagnosis of organic hyperinsulinism were surgically treated. Diagnosis was made with the combination of magnetic resonance imaging, computed tomography, selective angiography and intraoperative portal vein sampling. In five patients, the tumour was enucleated, in three patients Whipple procedure was performed; while three patients underwent left pancreatectomy with spleen preserving in two cases. The twelfth patient underwent total pancreatectomy following Whipple procedure performed elsewhere. There was no postoperative death. The complications were two pancreatic fistulas and two wound infections. The fasting pre- and postoperative plasma glucose mean value was 2.8 mm/l and 4.9 mm/l, respectively; while the pre- and postoperative plasma insulin mean value was 282 pm/l and 72 pm/l, respectively. Accurate diagnosis, preoperative localisation and diligent surgical exploration by experienced surgeons are the key to a successful outcome in patients with insulinomas.