Hyperinsulinism in the Neonate

Hypoglycemia in Children: Major Endocrine-Metabolic Causes and Novel Therapeutic Perspectives

Hypoglycemia is due to defects in the metabolic systems involved in the transition from the fed to the fasting state or in the hormone control of these systems. In children, hypoglycemia is considered a metabolic-endocrine emergency, because it may lead to brain injury, permanent neurological sequelae and, in rare cases, death. Symptoms are nonspecific, particularly in infants and young children. Diagnosis is based on laboratory investigations during a hypoglycemic event, but it may also require biochemical tests between episodes, dynamic endocrine tests and molecular genetics. This narrative review presents the age-related definitions of hypoglycemia, its pathophysiology and main causes, and discusses the current diagnostic and modern therapeutic approaches.

Congenital hyperinsulinemic hypoglycemia (HH) requiring treatment as the presenting feature of Kabuki syndrome

Kabuki syndrome is a congenital condition characterized by a set of facial dysmorphic features that often help the clinician to suspect the diagnosis. However, more insidious symptoms can rarely occur, such as manifestations of hypoglycemia in newborns with congenital hyperinsulinism hypoglycemia, especially when a variant of the KDM6A gene is found. In those cases, a treatment with diazoxide can be started and can be replaced with lanreotide if a satisfying glycemic control is not achieved. We report the case of a female patient born at 37 weeks of gestational age, without any obvious facial dysmorphic features, after a non-complicated pregnancy, that presented with feeding difficulties, drowsiness, and irritability revealing a hyperinsulinemic hypoglycemia. Further testing at 6 months old found a KDM6A mutation. The patient was initially treated by diazoxide alone, but its dosage had to be lowered because of the occurrence of treatment side effects, and lanreotide had been added to maintain acceptable blood sugar levels. A congenital hyperinsulinemia hypoglycemia revealed heterozygous truncating variant in the KDM6A gene, also known as X-linked Kabuki syndrome in a newborn. In cases of neonatal hypoglycemia, the first-line therapy is diazoxide. Our report shows that analogues of somatostatin such as lanreotide should be considered if the diazoxide regimen is not tolerated.

Glycaemic Imbalances in Seizures and Epilepsy of Paediatric Age: A Literature Review

Cerebral excitability and systemic metabolic balance are closely interconnected. Energy supply to neurons depends critically on glucose, whose fluctuations can promote immediate hyperexcitability resulting in acute symptomatic seizures. On the other hand, chronic disorders of sugar metabolism (e.g., diabetes mellitus) are often associated with long-term epilepsy. In this paper, we aim to review the existing knowledge on the association between acute and chronic glycaemic imbalances (hyper- and hypoglycaemia) with seizures and epilepsy, especially in the developing brain, focusing on clinical and instrumental features in order to optimize the care of children and adolescents and prevent the development of chronic neurological conditions in young patients.

Hyperinsulinism-hyperammonemia syndrome in two Peruvian children with refractory epilepsy

OBJECTIVES

Congenital hyperinsulinism (HI) is a heterogeneous clinical disorder with great variability in its clinical phenotype, and to date, pathogenic variants in 23 genes have been recognized.  Hyperinsulinism-hyperammonemia syndrome (HI/HA) is the second most frequent cause of this disease that shows an autosomal dominant pattern and is caused by an activating mutation of the GLUD1 gene, which responds favorably to the use of diazoxide. HI/HA syndrome presents with fasting hypoglycemia; postprandial hypoglycemia, especially in those with a high protein content (leucine); and persistent mild hyperammonemia. Neurological abnormalities, in the form of epilepsy or neurodevelopmental delay, are observed in a high percentage of patients; therefore, timely diagnosis is crucial for proper management.

CASE PRESENTATION

We report the clinical presentation of two Peruvian children that presented with epilepsy whose genetic analysis revealed a missense mutation in the GLUD1 gene, one within exon 11, at 22% mosaicism; and another within exon 7, as well as their response to diazoxide therapy. To the best of our knowledge, these are the first two cases of HI/HA syndrome reported in Peru.

CONCLUSIONS

HI/HA syndrome went unnoticed, because hypoglycemia was missed and were considered partially controlled epilepsies. A failure to recognize hypoglycemic seizures will delay diagnosis and adequate treatment, so a proper investigation could avoid irreversible neurological damage.

Congenital Hyperinsulinaemic Hypoglycaemia-A Review and Case Presentation

Hyperinsulinaemic hypoglycaemia (HH) is the most common cause of persistent hypoglycaemia in infants and children with incidence estimated at 1 per 50,000 live births. Congenital hyperinsulinism (CHI) is symptomatic mostly in early infancy and the neonatal period. Symptoms range from ones that are unspecific, such as poor feeding, lethargy, irritability, apnoea and hypothermia, to more serious symptoms, such as seizures and coma. During clinical examination, newborns present cardiomyopathy and hepatomegaly. The diagnosis of CHI is based on plasma glucose levels <54 mg/dL with detectable serum insulin and C-peptide, accompanied by suppressed or low serum ketone bodies and free fatty acids. The gold standard in determining the form of HH is fluorine-18-dihydroxyphenyloalanine PET ((18)F-DOPA PET). The first-line treatment of CHI is diazoxide, although patients with homozygous or compound heterozygous recessive mutations responsible for diffuse forms of CHI remain resistant to this therapy. The second-line drug is the somatostatin analogue octreotide. Other therapeutic options include lanreotide, glucagon, acarbose, sirolimus and everolimus. Surgery is required in cases unresponsive to pharmacological treatment. Focal lesionectomy or near-total pancreatectomy is performed in focal and diffuse forms of CHI, respectively. To prove how difficult the diagnosis and management of CHI is, we present a case of a patient admitted to our hospital.

Clinical Course and Outcome in Children with Congenital Hyperinsulinism

Background: Hyperinsulinism is the most common cause of persistent or recurrent neonatal hypoglycemia that may result in neurological deficits. The treatment goal in these patients is prevention of hypoglycemia to decrease mortality and morbidity. This study was done to determine the clinical course and outcome in children with congenital hyperinsulinism (CHI) referring to Mofid Children’s Hospital from 2011 to 2017. Methods: This study was done on 22 children with CHI referring to Mofid Children’s Hospital from 2011 to 2017. The demographic, perinatal, clinical, laboratory, imaging, pharmacological, treatment and follow up data of these children were collected and analyzed. Results: Among 22 children with CHI, the mortality rate was higher among those who received hydrocortisone versus those who did not receive hydrocortisone (46% versus 40%). Conclusion: According to the results of this study, hydrocortisone had a negative impact on the outcomes of these children, which is important in the management of hypoglycemia. The clinical course and outcome of children with CHI was better with medical compared to surgical treatment.

The coincidence of two rare diseases with opposite metabolic phenotype: a child with congenital hyperinsulinism and Bloom syndrome

OBJECTIVES

Congenital hyperinsulinism (CHI) is a group of rare genetic disorders characterized by insulin overproduction. CHI causes life-threatening hypoglycemia in neonates and infants. Bloom syndrome is a rare autosomal recessive disorder caused by mutations in the BLM gene resulting in genetic instability and an elevated rate of spontaneous sister chromatid exchanges. It leads to insulin resistance, early-onset diabetes, dyslipidemia, growth delay, immune deficiency and cancer predisposition. Recent studies demonstrate that the BLM gene is highly expressed in pancreatic islet cells and its mutations can alter the expression of other genes which are associated with apoptosis control and cell proliferation.

CASE PRESENTATION

A 5-month-old female patient from consanguineous parents presented with drug-resistant CHI and dysmorphic features. Genetic testing revealed a homozygous mutation in the KCNJ11 gene and an additional homozygous mutation in the BLM gene. While ¹⁸F-DOPA PET scan images were consistent with a focal CHI form and intraoperative frozen-section histopathology was consistent with diffuse CHI form, postoperative histopathological examination revealed features of an atypical form.

CONCLUSIONS

In our case, the patient carries two distinct diseases with opposite metabolic phenotypes.

The Role of GLP-1 Signaling in Hypoglycemia due to Hyperinsulinism

Incretin hormones play an important role in the regulation of glucose homeostasis through their actions on the beta cells and other tissues. Glucagon-like peptide-1 (GLP-1) and glucose dependent insulinotropic polypeptide (GIP) are the two main incretins and are secreted by enteroendocrine L- and K-cells, respectively. New evidence suggests that incretin hormones, particularly GLP-1, play a role in the pathophysiology of hyperinsulinemic hypoglycemia. In individuals with acquired hyperinsulinemic hypoglycemia after gastrointestinal surgery, including Nissen fundoplication and gastric bypass surgery, the incretin response to a meal is markedly increased and antagonism of the GLP-1 receptor prevents the hyperinsulinemic response. In individuals with congenital hyperinsulinism due to inactivating mutations in the genes encoding the beta cell K_ATP channels, the GLP-1 receptor antagonist, exendin-(9-39), increases fasting plasma glucose and prevents protein-induced hypoglycemia. Studies in human and mouse islets lacking functional K_ATP channels have demonstrated that the effect on plasma glucose is at least in part mediated by inhibition of insulin secretion resulting from lower cytoplasmic cAMP levels. The understanding of the role of incretin hormones in the pathophysiology of hyperinsulinemic hypoglycemia is important for the exploration of the GLP-1 receptor as a therapeutic target for these conditions. In this article, we will review incretin physiology and evidence supporting a role of the incretin hormones in the pathophysiology of hyperinsulinemic hypoglycemia, as well as results from proof-of concept studies exploring a therapeutic approach targeting the GLP-1 receptor to treat hyperinsulinemic hypoglycemia.

The Term Newborn: Hypoglycemia

This review provides an update on neonatal hypoglycemia in the term infant, including discussion of glucose metabolism, definitions of hypoglycemia, identification of infants commonly at risk, and the screening, treatment, and potential neurologic outcomes of postnatal hypoglycemia. Neonatal hypoglycemia is a common metabolic condition that continues to plague clinicians because there is no clear relationship between low glucose concentrations or their duration that determines adverse neurologic outcomes. However, severely low, prolonged, recurrent low glucose concentrations in infants who also have marked symptoms such as seizures, flaccid hypotonia with apnea, and coma clearly are associated with permanent brain damage. Early identification of at-risk infants, early and continued breastfeeding augmented with oral dextrose gel, monitoring prefeed glucose concentrations, treating symptomatic infants who have very low and recurrent low glucose concentrations, and identifying and aggressively managing infants with persistent hyperinsulinemia and metabolic defects may help prevent neuronal injury.

Neonatal Hypoglycemia and Brain Vulnerability

Neonatal hypoglycemia is a common condition. A transient reduction in blood glucose values is part of a transitional metabolic adaptation following birth, which resolves within the first 48 to 72 h of life. In addition, several factors may interfere with glucose homeostasis, especially in case of limited metabolic stores or increased energy expenditure. Although the effect of mild transient asymptomatic hypoglycemia on brain development remains unclear, a correlation between severe and prolonged hypoglycemia and cerebral damage has been proven. A selective vulnerability of some brain regions to hypoglycemia including the second and the third superficial layers of the cerebral cortex, the dentate gyrus, the subiculum, the CA1 regions in the hippocampus, and the caudate-putamen nuclei has been observed. Several mechanisms contribute to neuronal damage during hypoglycemia. Neuronal depolarization induced by hypoglycemia leads to an elevated release of glutamate and aspartate, thus promoting excitotoxicity, and to an increased release of zinc to the extracellular space, causing the extensive activation of poly ADP-ribose polymerase-1 which promotes neuronal death. In this review we discuss the cerebral glucose homeostasis, the mechanisms of brain injury following neonatal hypoglycemia and the possible treatment strategies to reduce its occurrence.

Necrotizing Enterocolitis in Neonates With Hyperinsulinemic Hypoglycemia Treated With Diazoxide

The most common cause of persistent hypoglycemia in the neonatal period is hyperinsulinism. Severe, refractory hypoglycemia resulting from hyperinsulinism can lead to significant brain injury and permanent cognitive disability. Diazoxide is the first-line and only US Food and Drug Administration-approved, pharmacologic treatment for refractory hyperinsulinism. In recent years, the use of diazoxide in neonates with persistent hyperinsulinemic hypoglycemia has increased in the United States. Known adverse effects of diazoxide include fluid retention, hypertrichosis, neutropenia, thrombocytopenia, and more recently, pulmonary hypertension. It is currently unknown if diazoxide exposure is associated with an increased risk of necrotizing enterocolitis (NEC) in neonates. We reviewed the cases of 24 patients in a level IV NICU at Massachusetts General Hospital who received diazoxide over 12 years (April 2006-April 2018). All 24 patients received enteral diazoxide for refractory hyperinsulinemic hypoglycemia. A total of 5 patients developed NEC after initiation of diazoxide based on clinical and radiographic findings, corresponding to 20% of infants exposed to diazoxide. This is above our baseline incidence of NEC (1% for all inborn infants and 6% for all inborn very low birth weight infants). More research and monitoring are necessary to characterize the potential risk of NEC associated with the use of diazoxide in the neonatal period.

Case Report: Two Distinct Focal Congenital Hyperinsulinism Lesions Resulting From Separate Genetic Events

Focal hyperinsulinism (HI) comprises nearly 50% of all surgically treated HI cases and is cured if the focal lesion can be completely resected. Pre-operative localization of the lesion is thus critical. Few cases of hyperinsulinism with multiple focal lesions have been reported, and assessment of the molecular mechanisms driving this rare occurrence has been limited. We present two cases of multifocal HI, each resulting from two independent, pancreatic focal lesions. ¹⁸Fluoro-dihydroxyphenylalanine positron emission tomography/computed tomography detected both lesions preoperatively in one patient, whereas identification of the second lesion was an incidental finding during surgical exploration in the other. Complete resection of the focal lesions resulted in cure of the HI in both cases. In each patient, genetic testing of the individual focal lesions revealed different regions of loss of heterozygosity for the maternal 11p15 allele, confirming that each lesion arose from independent somatic events in the setting of a paternally inherited germline ABCC8 mutation. These cases highlight the importance of a multidisciplinary and personalized approach to the management of infants with HI.

A comparison of the glycemic effects of glucagon using two dose ranges in neonates and infants with hypoglycemia

INTRODUCTION

Consensus regarding optimal glucagon dosing for management or diagnosis of neonatal/infant hypoglycemia has not been established.

OBJECTIVE

To investigate glycemic effects of glucagon dosed ≤0.2 mg/kg (Gn_low) vs. >0.2 mg/kg (Gn_high) in neonatal/infant hypoglycemia.

STUDY DESIGN

Retrospective, observational, cohort study.

RESULTS

Glucagon administration at any dose resulted in 75/77 (97.4%) samples meeting criteria for normoglycemia (plasma glucose >60 mg/dL), and plasma glucose increases of >30 mg/dL occurred in 74.2% vs. 63% (NS) of samples in the Gn_low and Gn_high groups, respectively. Despite equivalent glucagon dosing, there was a trend toward smaller (<2500 g) patients achieving post-glucagon plasma glucose increases of >30 mg/dL less often than their bigger (≥2500 g) counterparts (60% vs. 74.1%, NS).

CONCLUSIONS

Glucagon is highly effective in raising plasma glucose levels in neonatal/infant hypoglycemia. No differences in glycemic effects were noted between either dosing regimen. However, glycemic effects may be diminished in lower weight patients.

Higher C-peptide levels and glucose requirements may identify neonates with transient hyperinsulinism hypoglycemia who will benefit from diazoxide treatment

The aim of the study was to characterize factors that may serve as clinical tools to identify neonates with transient neonatal hyperinsulinism hypoglycemia (HH) who may benefit from diazoxide treatment. This retrospective study included 141 neonates with transient HH (93 males) of whom 34 (24%) were treated with diazoxide. Diazoxide treatment was started at median age of 13 days (range 5-35) and discontinued at median age of 42 days (range 14-224). The maximal dose was 7.1 ± 2.3 mg/kg/day. Diazoxide-treated neonates required a higher glucose infusion rate (GIR) compared with non-treated neonates (16.6 ± 3.4 vs. 10.4 ± 4.0 mg/kg/min, respectively, P < .01), had a longer duration of intravenous fluids (15.9 ± 9.3 vs. 7.8 ± 6.5 days, P < .01), a longer hospitalization (32.8 ± 22.7 vs. 20.4 ± 13.4 days, P < .01), a longer duration of carbohydrate supplementation (38.9 ± 40.4 vs. 17.8 ± 21.4 days, P < .01), and higher mean C-peptide levels on "critical sample" (1.4 ± 0.9 vs. 0.8 ± 0.5 ng/ml, P < .01). Their insulin levels also tended to be higher (3.5 ± 2.9 vs. 2.2 ± 3.8 μU/ml, P = .07). A stepwise logistic regression model revealed that significant predictors of prolonged HH were maximal GIRs (odds ratio (OR) 1.56, 95%; confidence interval (CI) 1.3-1.88, P < .001) and C-peptide levels (OR 3.57, 95%; CI 1.3-12.1, P = .005).Conclusion: Higher C-peptide levels and higher GIR requirements may serve as clinical tools to identify neonates with transient HH who may benefit from diazoxide treatment.What is Known:• Neonates with transient hyperinsulinism usually do not require treatment beyond glucose supplementation due to its self-limited clinical course, but some may benefit from diazoxide treatment.What is New:• Higher C-peptide levels and higher GIR requirements may serve as clinical tools to identify neonates with transient HH who may benefit from diazoxide treatment.• The incidence of prolonged neonatal HH is higher than the currently accepted figures.

Glucose Homeostasis in Newborns: An Endocrinology Perspective

Physiologic adaptations in the postnatal period, along with gradual establishment of enteral feeding, help maintain plasma glucose concentrations in the neonatal period. The definition of normal plasma glucose in the neonatal period has been a subject of debate because of a lack of evidence linking a set plasma or blood glucose concentration to clinical symptoms or predictors of short- and long-term outcomes. However, there is consensus that maintaining plasma glucose in the normal range for age is important to prevent immediate and long-term neurodevelopmental consequences of hypoglycemia or hyperglycemia. The specific management strategy for abnormal glucose levels in neonates depends on the underlying etiology, and interventions could include nutritional changes, medications, hormone therapy, or even surgery. Here, we will review the physiological processes that help maintain plasma glucose in newborns and discuss the approach to a newborn with disordered glucose homeostasis, with an emphasis on the endocrine basis of abnormal glucose homeostasis.

A Sensitive Plasma Insulin Immunoassay to Establish the Diagnosis of Congenital Hyperinsulinism

BACKGROUND

The diagnosis of congenital hyperinsulinism (CHI) may be hampered by a plasma (p-) insulin detection limit of 12-18 pmol/L (2-3 mU/L).

OBJECTIVE

To evaluate the diagnostic performance of a sensitive insulin immunoassay and to find the optimal p-insulin cut-off for the diagnosis of CHI.

METHODS

Diagnostic fasting tests, performed without medication or i.v.-glucose, were investigated in children with a clinical diagnosis of CHI, or idiopathic ketotic hypoglycemia (IKH). The CHI diagnosis was either clinical or by the alternative, p-insulin-free criteria; hypoglycemia plus disease-causing genetic mutations and/or CHI-compatible pancreatic histopathology. We included diagnostic p-insulin samples with simultaneous p-glucose <3.2 mmol/L and used a sensitive insulin assay (Cobas e411 immunoassay analyzer; lower detection limit 1.2 pmol/L; normal range 15.1-147.1 pmol/L). Receiver operating characteristics area under the curve (ROC AUC) values and optimal cut-offs were analyzed for the performance of p-insulin to diagnose CHI.

RESULTS

In 61 CHI patients, the median (range) p-insulin was 76.5 (17-644) pmol/L compared to 1.5 (1.5-7.7) pmol/L in IKH patients (n=15). The ROC AUC was 1.0 for the diagnosis of CHI defined both by the clinical diagnosis (n=61) and by alternative criteria (n=57). The optimal p-insulin cut-offs were 12.3 pmol/L, and 10.6 pmol/L, at p-glucose <3.2 mmol/L (n=61), and <3.0 mmol/L (n=49), respectively.

CONCLUSIONS

The sensitive insulin assay performed excellent in diagnosing CHI with optimal p-insulin cut-offs at 12.3 pmol/L (2.0 mU/L), and 10.6 pmol/L (1.8 mU/L), at p-glucose <3.2 mmol/L, and <3.0 mmol/L, respectively. A sensitive insulin assay may serve to simplify the diagnosis of CHI.

Severe, persistent neonatal hypoglycemia as a presenting feature in patients with congenital hypopituitarism: a review of our case series

Background Persistent hypoglycemia (PH) beyond 3 days of life warrants investigation which includes a critical sample. We report our case series of five neonates who presented with PH as the first sign of congenital hypopituitarism. Design This is a case series. Methods/Results This is a case series of five neonates evaluated at our academic institution in a 3-year period (2013-2016), who presented with persistent severe hypoglycemia and were subsequently diagnosed with congenital hypopituitarism. All neonates were full term (mean gestational age 39.8 ± 1.4 weeks) born by caesarian section with a mean weight of 3.5 ± 0.16 kg and a mean length of 51.2 ± 1.2 cm at birth. All five neonates had PH beyond 3 days with an average blood glucose (BG) <35 mg/dL at presentation, requiring a mean glucose infusion rate (GIR) of 7.22 ± 1.98 mg/kg/min. The average BG during the critical sample was 42 ± 0.16 mg/dL (three patients). The mean duration of requirement of the glucose infusion was 6.2 ± 3 days during the immediate neonatal period. Diagnosis of the hypopituitarism took 2-52 days from the initial presentation of hypoglycemia. Besides growth hormone (GH) deficiency, cortisol deficiency was diagnosed in all the five neonates. Neuroimaging findings in all the neonates were consistent with pituitary stalk interruption syndrome (hypoplastic anterior pituitary, ectopic posterior pituitary [EPP] and interrupted pituitary stalk). Conclusions Hypoglycemia is a common metabolic complication affecting an infant in the immediate neonatal period. Delay in the diagnosis of hypopituitarism presenting as hypoglycemia is the result of the lack of awareness among neonatologists and/or pediatricians. We propose that providers be cognizant that PH can be the only presentation of hypopituitarism in the neonatal period. Therefore, having a high index of suspicion about this condition can avoid a delay in the evaluation, diagnosis and treatment of hypopituitarism.