Persistent hyperinsulinaemic hypoglycaemia of infancy: long-term treatment with the somatostatin analogue Sandostatin

International Guidelines for the Diagnosis and Management of Hyperinsulinism

BACKGROUND

Hyperinsulinism (HI) due to dysregulation of pancreatic beta-cell insulin secretion is the most common and most severe cause of persistent hypoglycemia in infants and children. In the 65 years since HI in children was first described, there has been a dramatic advancement in the diagnostic tools available, including new genetic techniques and novel radiologic imaging for focal HI; however, there have been almost no new therapeutic modalities since the development of diazoxide.

SUMMARY

Recent advances in neonatal research and genetics have improved our understanding of the pathophysiology of both transient and persistent forms of neonatal hyperinsulinism. Rapid turnaround of genetic test results combined with advanced radiologic imaging can permit identification and localization of surgically-curable focal lesions in a large proportion of children with congenital forms of HI, but are only available in certain centers in "developed" countries. Diazoxide, the only drug currently approved for treating HI, was recently designated as an "essential medicine" by the World Health Organization but has been approved in only 16% of Latin American countries and remains unavailable in many under-developed areas of the world. Novel treatments for HI are emerging, but they await completion of safety and efficacy trials before being considered for clinical use.

KEY MESSAGES

This international consensus statement on diagnosis and management of HI was developed in order to assist specialists, general pediatricians, and neonatologists in early recognition and treatment of HI with the ultimate aim of reducing the prevalence of brain injury caused by hypoglycemia. A previous statement on diagnosis and management of HI in Japan was published in 2017. The current document provides an updated guideline for management of infants and children with HI and includes potential accommodations for less-developed regions of the world where resources may be limited.

Somatostatin receptors in congenital hyperinsulinism: Biology to bedside

Congenital hyperinsulinism (CHI), although a rare disease, is an important cause of severe hypoglycemia in early infancy and childhood, causing preventable morbidity and mortality. Prompt diagnosis and appropriate treatment is necessary to prevent hypoglycaemia mediated brain damage. At present, the medical treatment of CHI is limited to diazoxide as first line and synthetic somatostatin receptor ligands (SRLs) as second line options; therefore understanding somatostatin biology and treatment perspectives is important. Under healthy conditions, somatostatin secreted from pancreatic islet δ-cells reduces insulin release through somatostatin receptor induced cAMP-mediated downregulation and paracrine inhibition of β- cells. Several SRLs with extended duration of action are now commercially available and are being used off-label in CHI patients. Efficacy remains variable with the present generation of SRLs, with treatment effect often being compromised by loss of initial response and adverse effects such as bowel ischaemia and hepatobiliary dysfunction. In this review we have addressed the biology of the somatostatin system contexualised to CHI. We have discussed the clinical use, limitations, and complications of somatostatin agonists and new and emerging therapies for CHI.

Congenital Hyperinsulinism Caused by Novel Homozygous KATP Channel Gene Variants May Be Linked to Unexplained Neonatal Deaths among Kurdish Consanguineous Families

INTRODUCTION

Neonatal hypoglycemia due to congenital hyperinsulinism (CHI) is a potentially life-threatening condition. Biallelic pathogenic variants in KATP channel subunit genes (ABCC8, KCNJ11), causing severe forms of CHI, are more prevalent in regions with a significant rate of consanguinity and may lead to unexplained neonatal deaths. We hypothesized that KATP channel gene variants are the cause of CHI in three unrelated children from consanguineous Kurdish families with histories of four unexplained neonatal deaths with convulsions.

CASES

(1) A girl presented on the 6th day of life with recurrent hypoglycemic convulsions (blood glucose 2.05 mmol/L, insulin 58 mIU/L, C-peptide 2,242 pmol/L). (2) A girl with severe developmental delay was diagnosed with CHI at 3 years of age (blood glucose 2.78 mmol/L, insulin 8.1 mIU/L, C-peptide 761 pmol/L) despite a history of recurrent hypoglycemia since neonatal age. (3) A girl presented at 3 weeks of age with convulsions and unconsciousness (blood glucose 2.5 mmol/L, insulin 14.6 mIU/L, C-peptide 523 pmol/L). Coding regions of the ABCC8 and KCNJ11 genes were tested by Sanger sequencing. Potential variants were evaluated using the American College of Medical Genetics standards. Three novel causative homozygous variants were found - p.Trp514Ter in the ABCC8 gene (Pt2), and p.Met1Val (Pt1) and p.Tyr26Ter (Pt3) in the KCNJ11 gene.

CONCLUSION

CHI caused by KATP channel variants was elucidated in three children, providing a highly probable retrospective diagnosis for their deceased siblings. Future lives can be saved by timely diagnosis of CHI when encountering a neonate with unexplained seizures or other signs of recurrent and/or persistent hypoglycemia.

Somatostatin analogues for the treatment of hyperinsulinaemic hypoglycaemia

Hyperinsulinaemic hypoglycaemia (HH) is a biochemical finding of low blood glucose levels due to the dysregulation of insulin secretion from pancreatic β-cells. Under normal physiological conditions, glucose metabolism is coupled to β-cell insulin secretion so that blood glucose levels are maintained within the physiological range of 3.5-5.5 mmol/L. However, in HH this coupling of glucose metabolism to insulin secretion is perturbed so that insulin secretion becomes unregulated. HH typically occurs in the neonatal, infancy and childhood periods and can be due to many different causes. Adults can also present with HH but the causes in adults tend to be different. Somatostatin (SST) is a peptide hormone that is released by the delta cells (δ-cells) in the pancreas. It binds to G protein-coupled SST receptors to regulate a variety of location-specific and selective functions such as hormone inhibition, neurotransmission and cell proliferation. SST plays a potent role in the regulation of both insulin and glucagon secretion in response to changes in glucose levels by negative feedback mechanism. The half-life of SST is only 1-3 min due to quick degradation by peptidases in plasma and tissues. Thus, a direct continuous intravenous or subcutaneous infusion is required to achieve the therapeutic effect. These limitations prompted the discovery of SST analogues such as octreotide and lanreotide, which have longer half-lives and therefore can be administered as injections. SST analogues are used to treat different forms of HH in children and adults and therapeutic effect is achieved by suppressing insulin secretion from pancreatic β-cells by complex mechanisms. These treatments are associated with several side effects, especially in the newborn period, with necrotizing enterocolitis being the most serious side effect and hence SS analogues should be used with extreme caution in this age group.

Hyperinsulinemic hypoglycemia: clinical, molecular and therapeutical novelties

Hyperinsulinemic hypoglycemia (HI) is the most common cause of hypoglycemia in children. Impairment of cellular pathways involved in insulin secretion from pancreatic β-cells, broadly classified as channelopathies and metabolopathies, have been discovered in the past two decades. The increasing use of NGS target panels, combined with clinical, biochemical and imaging findings allows differentiating the diagnostic management of children with focal forms, surgically curable, from those with diffuse forms, more conservatively treated with pharmacological and nutritional interventions. Specific approaches according to the subtype of HI have been established and novel therapies are currently under investigation. Despite diagnostic and therapeutic advances, HI remains an important cause of morbidity in children, still accounting for 26-44% of permanent intellectual disabilities, especially in neonatal-onset patients. Initial insult from recurrent hypoglycemia in early life greatly contributes to the poor outcomes. Therefore, patients need to be rapidly identified and treated aggressively, and require at follow-up a complex and regular monitoring, managed by a multidisciplinary HI team. This review gives an overview on the more recent diagnostic and therapeutic tools, on the novel drug and nutritional therapies, and on the long-term neurological outcomes.

Long-term medical treatment in congenital hyperinsulinism: a descriptive analysis in a large cohort of patients from different clinical centers

BACKGROUND

Up to now, only limited data on long-term medical treatment in congenital hyperinsulinism (CHI) is available. Moreover, most of the drugs used in CHI are therefore not approved. We aimed to assemble more objective information on medical treatment in CHI with regard to type and duration, dosage as well as side effects.

METHODS

We searched MEDLINE (from 1947) and EMBASE (from 1988) using the OVID interface for relevant data to evaluate medical treatment in a large cohort of patients with CHI from different clinical centers. Randomized, controlled trials were not available. We evaluated case reports and case series. No language restrictions were made.

RESULTS

A total number of 619 patients were medically treated and information regarding conservative treatment was available. Drugs used were diazoxide (in 84% of patients), somatostatin analogues (16%), calcium channel antagonists (4%) and glucagon (1%). Mean dose of diazoxide was 12.5 (±4.3) mg/kg ⋅ d (range 2-60 mg/kg ⋅ d), mean duration of diazoxide treatment until remission was 57 months. Side effects of diazoxide were usually not severe. The causal relation between diazoxide and severe side effects, e.g. heart failure (3.7%) remains doubtful. Mean dose of octreotide was 14.9 (±7.5) μg/kg ⋅ d (range 2.3-50 μg/kg ⋅ d), of lanreotide 67.3 (±39.8) mg ⋅ month (range 10-120 mg ⋅ month). Mean duration of treatment with somatostatin analogues until remission was 49 months. Frequent side effects included tachyphylaxis and mild gastrointestinal symptoms. The risk of persistent growth deceleration was low (<5%).

CONCLUSIONS

Severe side effects are rare and a causal relation remains disputable. We conclude that long-term conservative treatment of CHI is feasible.

Nifedipine in Congenital Hyperinsulinism - A Case Report

Congenital hyperinsulinism (CHI) is the commonest cause of persistent hypoglycemia in neonates. Diazoxide is the first-line drug in its treatment, but the more severe cases are usually diazoxide-resistant. Recessive ABCC8 and KCNJ11 mutations are responsible for most (82%) of the severe diazoxide-unresponsive CHI. Oral nifedipine has been effective in isolated cases of CHI. Successful treatment of diazoxide-unresponsive CHI with a combination of octreotide and nifedipine has been reported in a single isolated case so far. We report here a case of diazoxide-resistant CHI due to homozygous ABCC8 nonsense mutation. In this case, hypoglycaemia uncontrolled by pancreatectomy and octreotide alone showed a good response to a combination of nifedipine and octreotide. Octreotide was tapered off by one year age and thereafter the child is euglycaemic on oral nifedipine alone. Continuous glucose monitoring sensor was used as an aid to monitor glycaemic control and was found to be a safe and reliable option reducing the number of needle-pricks in small children.

PK study of octreotide based on LC–MS/MS combining protein precipitation and impurity extraction technique

Aim: To establish a robust methodology for quantitative analysis of therapeutic peptide in biological samples. Materials & Methods: Octreotide was chosen as a model therapeutic peptide, and oxidized-octreotide was synthesized as internal standard. Protein precipitation combining liquid-liquid extraction technique was adopted to enhance the recovery and reduce the endogenous interferences effectively. A LC–MS/MS method for the quantification of octreotide in plasma has been optimized and validated according to FDA guidelines. Results: Linearity, selectivity, accuracy, precision, stability, matrix effect and recovery were within bioanalytical method validation acceptance criteria as FDA guidelines. The methodology was then successfully applied into the studies for octreotide. Conclusion: This robust methodology would be useful for the PK studies for octreotide and other therapeutic peptides.

Management strategies for neonatal hypoglycemia

While hypoglycemia occurs commonly among neonates, treatment can be challenging if hypoglycemia persists beyond the first few days of life. This review discusses the available treatment options for both transient and persistent neonatal hypoglycemia. These treatment options include dextrose infusions, glucagon, glucocorticoids, diazoxide, octreotide, and nifedipine. A stepwise, practical approach to the management of these patients is offered.

A combination of nifedipine and octreotide treatment in an hyperinsulinemic hypoglycemic infant

Hyperinsulinemic hypoglycemia (HH) is the commonest cause of persistent hypoglycemia in the neonatal and infancy periods. Mutations in the ABCC8 and KCNJ11 genes, which encode subunits of the ATP-sensitive potassium channel in the pancreatic beta cell, are identified in approximately 50% of these patients. The first-line drug in the treatment of HH is diazoxide. Octreotide and glucagon can be used in patients who show no response to diazoxide. Nifedipine, a calcium-channel blocker, has been shown to be an effective treatment in a small number of patients with diazoxide-unresponsive HH. We report a HH patient with a homozygous ABCC8 mutation (p.W1339X) who underwent a near-total pancreatectomy at 2 months of age due to a lack of response to diazoxide and octreotide treatment. Severe hypoglycemic attacks continued following surgery, while the patient was being treated with octreotide. These attacks resolved when nifedipine was introduced. Whilst our patient responded well to nifedipine, the dosage could not be increased to 0.75 mg/kg/day due to development of hypotension, a reported side effect of this drug. Currently, our patient, now aged 4 years, is receiving a combination of nifedipine and octreotide treatment. He is under good control and shows no side effects. In conclusion, nifedipine treatment can be started in patients with HH who show a poor response to diazoxide and octreotide treatment.

Subtotal Pancreatectomy for Congenital Hyperinsulinism: Our Experience and Review of Literature

Congenital hyperinsulinism (HI) is characterized by profound hypoglycemia caused by inappropriate insulin secretion. HI is a heterogeneous disorder with at least two histologic lesions and several implicated genes. If HI is caused by a focal lesion, elective surgery is the treatment of choice because it leads to complete recovery without diabetes. On the contrary, near-total pancreatectomy though recommended for diffuse HI, long-term risks of endocrine and exocrine deficiencies are present. Between the years 2006-2011, three patients of HI were referred to and operated by a single surgeon. The preoperative diagnosis was confirmed by recurrent hypoglycemia, inappropriately high insulin levels, and augmented glucose requirements. The medical records of all three patients were reviewed to study their clinical features, medical and surgical treatment, and postoperative outcome (short- and long-term). There were three patients in this series (male/female ratio, 1:2), all presenting in the neonatal age. All patients failed medical treatment, and radiological imaging did not reveal any pancreatic lesion. All patients underwent subtotal (80 %) pancreatectomy. Two patients had diffuse type of HI and one focal HI. One patient had transient hyperglycemia for 3 months, which needed insulin supplementation. No patient has developed recurrent hypoglycemia, malabsorption syndrome, or any neurological sequelae until the last follow-up. Doing subtotal or near-total pancreatectomy in diffuse type of HI still remains controversial as one has a higher risk of recurrent hypoglycemia, while the other has a higher rate of insulin dependent diabetes mellitus. Subtotal (80 %) pancreatectomy may be considered as the primary modality of surgical intervention in diffuse type of HI, especially when the diagnostic facilities are limited or diagnosis is not known after preliminary investigations. This minimizes the chances of postoperative diabetes mellitus, and redo surgery can always be considered if there is recurrent hypoglycemia.

Hyperinsulinaemic hypoglycaemia:genetic mechanisms, diagnosis and management

Hyperinsulinaemic hypoglycaemia (HH) is characterized by unregulated insulin secretion from pancreatic β-cells. Untreated hypoglycaemia in infants can lead to seizures, developmental delay, and subsequent permanent brain injury. Early identification and meticulous managementof these patients is vital to prevent neurological insult. Mutations in eight different genes (ABCC8, KCNJ11, GLUD1, CGK, HADH, SLC16A1, HNF4A and UCP2) have been identified to date in patients with congenital forms of hyperinsulinism (CHI). The most severe forms of CHI are due to mutations in ABCC8 and KCJN11, which encode the two components of pancreatic β-cell ATP-sensitive potassium channel. Recent advancement in understanding the genetic aetiology, histological characterisation into focal and diffuse variety combined with improved imaging (such as fluorine 18 L-3, 4-dihydroxyphenylalanine positron emission tomography 18F-DOPA-PET scanning) and laparoscopic surgical techniques have greatly improved management. In adults, HH can be due to an insulinoma, pancreatogenous hypoglycaemic syndrome, post gastric-bypass surgery for morbid obesity as well as to mutations in insulin receptor gene. This review provides an overview of the molecular basis of CHI and outlines the clinical presentation, diagnostic criteria, and management of these patients.

Persistent hyperinsulinemic hypoglycemia of infancy: An overview of current concepts

Persistent hyperinsulinemic hypoglycemia of infancy (PHHI) is relatively rare but one of the most important causes of severe neonatal hypoglycemia. Recognition of this entity becomes important due to the fact that the hypoglycemia is so severe and frequent that it may lead to severe neurological damage in the infant manifesting as mental or psychomotor retardation or even a life-threatening event if not recognized and treated effectively in time. Near-total pancreatectomy may be required for patients with intractable hypoglycemia despite medical treatment; however, that may result in diabetes mellitus or recurrent postoperative hypoglycemia. This review aims to consolidate the traditional concepts and current information related to the pathogenesis and management of PHHI.

Hyperinsulinaemic hypoglycaemia: genetic mechanisms, diagnosis and management

Hyperinsulinaemic hypoglycaemia (HH) is due to the unregulated secretion of insulin from pancreatic β-cells. A rapid diagnosis and appropriate management of these patients is essential to prevent the potentially associated complications like epilepsy, cerebral palsy and neurological impairment. The molecular basis of HH involves defects in key genes (ABCC8, KCNJ11, GLUD1, GCK, HADH, SLC16A1, HNF4A and UCP2) which regulate insulin secretion. The most severe forms of HH are due to loss of function mutations in ABCC8/KCNJ11 which encode the SUR1 and KIR6.2 components respectively of the pancreatic β-cell K(ATP) channel. At a histological level there are two major forms (diffuse and focal) each with a different genetic aetiology. The diffuse form is inherited in an autosomal recessive (or dominant) manner whereas the focal form is sporadic in inheritance and is localised to a small region of the pancreas. The focal form can now be accurately localised pre-operatively using a specialised positron emission tomography scan with the isotope Fluroine-18L-3, 4-dihydroxyphenyalanine (18F-DOPA-PET). Focal lesionectomy can provide cure from the hypoglycaemia. However the diffuse form is managed medically or by near total pancreatectomy (with high risk of diabetes mellitus). Recent advances in molecular genetics, imaging with 18F-DOPA-PET/CT and novel surgical techniques have changed the clinical approach to patients with HH.

Therapeutic applications of octreotide in pediatric patients

BACKGROUND/AIM

We report our experience with the use of octreotide as primary or adjunctive therapy in children with various gastrointestinal disorders.

PATIENTS AND METHODS

A pharmacy database identified patients who received octreotide for gastrointestinal diseases. Indications for octreotide use, dosing, effectiveness, and adverse events were evaluated by chart review.

RESULTS

A total of 21 patients (12 males), aged 1 month to 13 years, were evaluated. Eleven received octreotide for massive gastrointestinal bleeding caused by portal hypertension-induced lesions (n=7), typhlitis (1), Meckel's diverticulum (1), and indefinite source (2). Blood transfusion requirements were reduced from 23 ± 9 mL/kg (mean ± SD) to 8 ± 15 mL/kg (P<0.01). Four patients with pancreatic pseudocyst and/or ascites received octreotide over 14.0 ± 5.7 days in 2 patients. In 3 children, pancreatic pseudocyst resolved in 12 ± 2 days and pancreatic ascites resolved in 7 days in 2. Three patients with chylothorax received octreotide for 14 ± 7 days with complete resolution in each. Two infants with chronic diarrhea received octreotide over 11 ± 4.2 months. Stool output decreased from 85 ± 21 mL/kg/day to 28 ± 18 mL/kg/day, 3 months after initiation of octreotide. The child with dumping syndrome responded to octreotide in a week. Adverse events developed in 4 patients: Q-T interval prolongation and ventricular fibrillation, hyperglycemia, growth hormone deficiency, and hypertension.

CONCLUSION

Octreotide provides a valuable addition to the therapeutic armamentum of the pediatric gastroenterologist for a wide variety of disorders. Serious adverse events may occur and patients must be closely monitored.

Neuroendocrine tumors in children and young adults: rare or not so rare

This review focuses on neuroendocrine tumors (NETs) that arise in the diffuse neuroendocrine system; these rare tumors can develop in any organ that has dispersed single endocrine cells, for example, the intestine, or in an organ that has clusters of endocrine cells, for example, pancreatic islets. Previously considered benign, NETs are now recognized to recur locally or metastasize to liver and bone if not completely excised early in their course of development. This article summarizes the epidemiology and reviews the diagnostic and therapeutic challenges of NETs in children and youth, noting especially those NETs that are more prevalent in young people than in older adults.

Glucose metabolism and neurological outcome in congenital hyperinsulinism

Advances in imaging and surgical techniques allow a complete cure for children with focal-type congenital hyperinsulinism (CHI). In contrast, management of diffuse-type CHI remains a matter of controversy. To prevent hypoglycemic brain damage, extensive surgery has been recommended in the past, resulting in diabetes. On the basis of 2 data sets of patients with congenital hyperinsulinism, the German registry for CHI with 235 patients (ages 1 day to 19 years) and the diabetes treatment register (Diabetes Patienten-Verlaufsdokumentationssystem initiative), a follow-up study was initiated for diabetes mellitus and the intellectual and physical development as well as motor function. In our ongoing study, we investigated 20 patients with CHI (12 male, mean ages 9.9 years). Six of 20 patients had undergone subtotal pancreatectomy. In early infantile development (0-3 years) we observed a trend to motor and speech delay. In early childhood (2.5-7 years) there appeared a trend to an advantage of results of nonverbal tasks compared with verbal tasks. Before 1990 most patients (∼75%) were treated by subtotal pancreatectomy; since 2000, a more conservative approach is obvious (4/68). All patients with diabetes (n = 25) developed the condition after undergoing subtotal pancreatectomy. No spontaneous manifestation of diabetes was noted before adulthood. There was a wide range of age (0-17.7 years) at manifestation indicating a long period during which glucose tolerance is compensated. Compared with >40.000 children with type 1 diabetes mellitus from the Diabetes Patienten-Verlaufsdokumentationssystem registry, we found significant differences with a tendency for being overweight as well as small stature. Mean daily insulin dose and HbA1c was comparable in both groups.

Hyperinsulinism in Infancy: From Basic Science to Clinical Disease

Dunne, Mark J., Karen E. Cosgrove, Ruth M. Shepherd, Albert Aynsley-Green, and Keith J. Lindley. Hyperinsulinism in Infancy: From Basic Science to Clinical Disease. Physiol Rev 84: 239–275, 2004; 10.1152/physrev.00022.2003.—Ion channelopathies have now been described in many well-characterized cell types including neurons, myocytes, epithelial cells, and endocrine cells. However, in only a few cases has the relationship between altered ion channel function, cell biology, and clinical disease been defined. Hyperinsulinism in infancy (HI) is a rare, potentially lethal condition of the newborn and early childhood. The causes of HI are varied and numerous, but in almost all cases they share a common target protein, the ATP-sensitive K+channel. From gene defects in ion channel subunits to defects in β-cell metabolism and anaplerosis, this review describes the relationship between pathogenesis and clinical medicine. Until recently, HI was generally considered an orphan disease, but as parallel defects in ion channels, enzymes, and metabolic pathways also give rise to diabetes and impaired insulin release, the HI paradigm has wider implications for more common disorders of the endocrine pancreas and the molecular physiology of ion transport.

Two cases of persistent hyperinsulinemic hypoglycemia that showed spontaneous regression and maturation of the Langerhans islets

Near-total pancreatectomy has been recommended as the treatment for persistent hyperinsulinemic hypoglycemia (PHH) in infants. However, recently there has been a report described that one third of 95% pancreatectomy failed to prevent hypoglycemia and more than two thirds had diabetes ultimately. The authors experienced 2 cases of PHH, which raise a query about the extensive pancreatectomy. Case 1: A female patient who manifested PHH shortly after birth underwent less extensive pancreatectomy twice at age 2 months and 8 years. After each operation, her clinical symptoms regressed, and she became free from the disease eventually. Histologic findings showed nesidioblastosis in which the islets clearly matured. Case 2: A male infant with PHH had an absolute indication for pancreatectomy. However, after a meticulous control of the blood glucose level with parenteral nutrition followed by continuous enteral nutrition feeding combined with medication, he became free from the disease. The current cases show there exist cases of PHH in which the islets mature and symptoms regress spontaneously. Therefore, we conclude near-total pancreatectomy is not always the treatment of choice. As an alternate strategy, long-term controlled feeding and medication combined with or without less extensive pancreatectomy should be considered with the expectation of spontaneous regression.

Hyperinsulinism of the newborn

Neonatal hyperinsulinism (HI) is a clinical syndrome of pancreatic beta-cell dysfunction characterized by failure to suppress insulin secretion in the presence of hypoglycemia. Although rare, it is the most common cause for persistent hypoglycemia in the newborn period. Treatment can be extremely difficult, and partial pancreatectomy is frequently required to prevent recurrent hypoglycemia and irreversible brain damage. In the last 5 years much has been learned about the pathophysiology of this disease. In most patients, the disease is caused by recessive mutations in either of the 2 functional subunits of the beta-cell KATP channel (SUR1 or Kir6.2). Although in most families, the disease is transmitted as an autosomal recessive trait, a novel form of transmission, resulting in focal involvement of the pancreas has recently been described. Not all patients with HI have mutations in the KATP channel genes. An activating mutation in the "glucose sensor" glucokinase has recently been reported in one family with diazoxide-responsive autosomal dominant hyperinsulinemic hypoglycemia. Also, a new syndrome of hyperinsulinism associated with benign hyperammonemia was recently described and found to be caused by activating mutations in the glutamate dehydrogenase (GDH) gene (GLUD-1). Thus, the clinical syndrome of HI can be caused by mutations in 4 different genes and can be transmitted as either a recessive or a dominant trait. These findings aid in the therapeutic decision-making process and improve the accuracy and precision of genetic counseling. Despite these recent discoveries, however, the metabolic origin of the disease is still unknown in about 50% of cases.

Hypoglycemia in infants and children

Hypoglycemia is more common in the pediatric patient than in adults. This article discusses the many diagnoses that can be associated with hypoglycemia in infancy and childhood. A guide to help practitioners evaluate such patients and suggested treatments for many of these disorders are provided. As genetic diagnosis continues to develop, it is anticipated that the list of specific disorders associated with hypoglycemia in infancy and childhood will increase.

Clinical use of the long acting somatostatin analogue octreotide in pediatrics

Preliminary data of the use of the long-acting somatostatin analog octreotide (Sandostatin) in pediatrics are reported. In nesidioblastosis and other hyperinsulinemic conditions, timely treatment with octreotide can protect cerebral function and may reduce mortality. The acute use of octreotide produces prompt elevation of blood glucose, even in patients who fail to respond to diazoxide. In addition, it may be possible to avoid the need for partial or subtotal pancreatectomy by the long-term use of octreotide. As in adults, octreotide should find a place in the symptomatic treatment of secretory diarrhea, notably the watery diarrhea hypokalemia-achlorhydria complex and pancreatic cholera syndrome. Octreotide has been shown to be effective in the treatment of familial tall stature by reducing height velocity and final height. Responses to octreotide therapy vary and the individual responsiveness must be extensively studied.

Persistent hyperinsulinemic hypoglycemia of infancy: long-term octreotide treatment without pancreatectomy

Eight patients with persistent hyperinsulinemic hypoglycemia of infancy who were treated with octreotide without pancreatectomy are described. All had severe, early-onset disease that would have required partial pancreatectomy had octreotide not been available. Along with octreotide, frequent feedings and raw cornstarch at night were required by all. Octreotide was given in three or four daily subcutaneous injections in four patients and in a continuous subcutaneous infusion with an insulin infusion pump in four. All had mild, transient gastrointestinal symptoms (vomiting, abdominal distention, steatorrhea) after the start of therapy. Asymptomatic gallstones were found in 1 patient after 1 year of treatment. No other long-term untoward effects were noted, including no detrimental effect on psychomotor development. Growth was not affected in five of six patients treated for more than 6 months. In five patients, octreotide was discontinued after 9 months to 5 1/2 years; patients were given diazoxide instead, two required percutaneous gastrostomy, and one 5 1/2-year-old child required no further treatment. The remaining three patients (aged 5 to 9 months) are still being treated with octreotide. We conclude that, with the use of octreotide, pancreatectomy can be avoided in some patients. Particularly in light of our findings of a high incidence of diabetes years after partial pancreatectomy, and clinical improvement after months to years of octreotide treatment, we believe that aggressive medical therapy, when effective, is preferable to partial pancreatectomy.

Effects of octreotide on circulating islet B cell products in endogenous hyperinsulinism

The role of somatostatin analogues in the medical management of insulinomas is unclear. We describe an elderly patient with clinical and biochemical features of endogenous hyperinsulinism attributable to a benign islet B cell disorder whose incapacitating neuroglycopaenic symptoms responded dramatically to octreotide 50 micrograms subcutaneously at 2200 h each night. Octreotide suppressed inappropriate plasma concentrations of insulin thereby preventing fasting hypoglycaemia. Fasting concentrations of proinsulin, and 32-33 split proinsulin, as determined by two-site monoclonal antibody-based immunoradiometric assays, were also suppressed by octreotide.

Persistent hyperinsulinemic hypoglycemia of infancy ("nesidioblastosis"): autosomal recessive inheritance in 7 pedigrees

Persistent Hyperinsulinemic Hypoglycemia of Infancy (PHHI) is a rare disease characterized clinically by persistent hypoglycemia with inappropriately elevated circulating insulin concentrations. Here we report on 7 pedigrees including 21 cases. The pedigrees are derived from 3 distinct ethnic groups, and include a very large Bedouin family, and Arab family, and 5 smaller pedigrees of Jewish families all of Eastern European origin. Data obtained from these families and from other families reported in the literature strongly suggest that PHHI is inherited as an autosomal recessive disorder.

Regulation of insulin release in persistent hyperinsulinaemic hypoglycaemia of infancy studied in long-term culture of pancreatic tissue

Pancreatic tissue was obtained during therapeutic subtotal pancreatectomy from five infants with persistent hyperinsulinaemic hypoglycaemia of infancy (so-called nesidioblastosis). Collagenase digests of the specimens were cultured in RPMI 1640 medium on extracellular matrix-coated plates. Acute insulin secretion showed minimal sensitivity to changes in glucose concentration. Sensitivity to other nutrient secretagogues such as glyceraldehyde, leucine, alpha-ketoisocaproic acid and arginine was variable, showing either diminished or absent response. On the other hand, stimulators of Beta cell cAMP and modulators of the phosphoinositide-protein kinase C pathway were effective inducers of insulin release. The response to cAMP stimulators was independent of the glucose concentration. Although insulin output was high in the absence of glucose, this was not due to passive leak of hormone, since both removal of calcium and addition of somatostatin and epinephrine inhibited the secretion. Beta cells were more sensitive to somatostatin than epinephrine; however, both agents failed to completely suppress the release even at suprapharmacological concentrations. Although it cannot be excluded that the culture conditions affected Beta cell function, the present findings may suggest that cultured Beta cells in persistent hyperinsulinaemic hypoglycaemia of infancy behave like fetal Beta cells at early developmental stages.