Clinical and laboratory characteristics and follow up of 62 cases of ketotic hypoglycemia: a retrospective study

Approach to the Patient: Investigation of Pediatric Hypoglycemia in the Emergency Department-A Practical Algorithm

Hypoglycemia in the pediatric population tends to present in the newborn period or during metabolic crisis triggered by prolonged fasting and intercurrent illness. Current recommendations to investigate all children presenting with hypoglycemia for the first time are cumbersome and costly but necessary to identify those with serious conditions who predispose to hypoglycemia. We describe a practical and cost-effective method of evaluating children who present to the emergency department with previously undiagnosed hypoglycemia. Glucose and point-of-care (POC) beta-hydroxybutyrate levels should be measured on all children with a low screening POC glucose level, and a full history and physical examination will identify those requiring further investigation. This approach is suggested to identify patients with serious and life-threatening disease with the same fidelity as the currently recommended approach of performing a critical sample on all children with hypoglycemia. Our streamlined approach will reduce the cost to approximately 10% of the current approach per patient diagnosed with a serious underlying disease. Further, children without underlying hypoglycemia-predisposing disorders will be identified and discharged without unnecessary intervention.

Idiopathic ketotic hypoglycemia in children: an update

Idiopathic ketotic hypoglycemia (IKH) is defined as bouts of hypoglycemia with increased blood or urine ketones in certain children after prolonged fasting or during illness. IKH is divided into physiological IKH, which is most frequently observed in normal children with intercurrent acute illness, and pathological IKH, which occurs in children who lack counter-regulatory hormones, have a metabolic disease, or have Silver-Russell syndrome. The typical patient is a young child between the ages of 10 months and 6 years. Episodes nearly always occur in the morning after overnight fasting. Symptoms include those of neuroglycopenia, ketosis, or both. IKH may be diagnosed after ruling out various metabolic and hormonal conditions associated with ketotic hypoglycemia. Sufficient amounts of carbohydrates and protein, avoidance of prolonged fasting, and increased frequency of food ingestion are the main modes of treating IKH. It is crucial to understand the pathogenesis of IKH and to distinguish physiological IKH from pathological IKH. In this mini-review, we present a brief summary of IKH in terms of its definition, types, clinical presentation, diagnosis, and therapeutic approach in children.

Idiopathic Pathological Ketotic Hypoglycemia: Finding the Needle in a Haystack

Sick children often have a decreased appetite and experience vomiting and diarrhea; however, hypoglycemia (plasma glucose concentration ≤50 mg/dL or 2.8 mmol/L) is rare. Ketotic hypoglycemia (KH) is the most common cause of hypoglycemia presenting to an Emergency Department in a previously healthy child between 6 months and 6 years of age. Ketosis and hypoglycemia are now well understood to be normal physiologic responses of young children to prolonged fasting.There is now substantial evidence that the term KH describes a variety of conditions including both the lower end of the normal distribution of fasting tolerance in young children as well as numerous rare disorders that impair fasting adaptation. Recent advances in molecular genetic testing have led to the discovery of these rare disorders. Idiopathic pathological KH is a diagnosis of exclusion that describes rare children who have abnormally limited fasting tolerance, experience recurrent episodes of KH, or develop symptoms of hypoglycemia despite elevated ketone levels, and in whom an explanation cannot be found despite extensive investigation. This review provides an approach to distinguishing between physiological KH and pathological KH and includes recommendations for management.

Hypoglycaemia Metabolic Gene Panel Testing

A large number of inborn errors of metabolism present with hypoglycemia. Impairment of glucose homeostasis may arise from different biochemical pathways involving insulin secretion, fatty acid oxidation, ketone bodies formation and degradation, glycogen metabolism, fructose and galactose metabolism, branched chain aminoacids and tyrosine metabolism, mitochondrial function and glycosylation proteins mechanisms. Historically, genetic analysis consisted of highly detailed molecular testing of nominated single genes. However, more recently, the genetic heterogeneity of these conditions imposed to perform extensive molecular testing within a useful timeframe via new generation sequencing technology. Indeed, the establishment of a rapid diagnosis drives specific nutritional and medical therapies. The biochemical and clinical phenotypes are critical to guide the molecular analysis toward those clusters of genes involved in specific pathways, and address data interpretation regarding the finding of possible disease-causing variants at first reported as variants of uncertain significance in known genes or the discovery of new disease genes. Also, the trio's analysis allows genetic counseling for recurrence risk in further pregnancies. Besides, this approach is allowing to expand the phenotypic characterization of a disease when pathogenic variants give raise to unexpected clinical pictures. Multidisciplinary input and collaboration are increasingly key for addressing the analysis and interpreting the significance of the genetic results, allowing rapidly their translation from bench to bedside.

Starvation Ketosis in the Pediatric Emergency Department: A Prospective Estimate of Prevalence

OBJECTIVES

Starvation ketosis may occur in children during intercurrent illnesses due to metabolic adaptation to fasting, resulting in significant ketonemia and sometimes ketoacidosis. Also known as accelerated starvation, common symptoms are vomiting, lethargy, and seizures. Previous studies found the prevalence of ketotic hypoglycemia to be 4 per 100,000 presentations to the emergency department (ED). We hypothesized that the prevalence had been underestimated due to the retrospective nature and restricted definitions of previous studies. Our aim was to determine if a prospective study would confirm a higher prevalence of starvation ketosis in pediatric patients presenting to the ED.

METHODS

A prospective observational study of consecutive patients was performed in an urban pediatric ED utilizing point-of-care testing of capillary blood glucose and ketones in symptomatic children.

RESULTS

This study found the prevalence of clinically significant ketosis (defined as beta-hydroxybutyrate 2.5 mmol/L or more) to be approximately 1800 per 100,000 ED presentations, with more than 170 per 100,000 also being hypoglycemic. Affected patients were 3 months to 9 years of age. Fifty-five percent of the presentations were boys, and 56% were under the 50th centile for weight.

CONCLUSIONS

This prospective observational study using a targeted testing regimen found the prevalence of both starvation ketosis and hypoglycemia to be much greater than previous studies which used retrospective analyses. A simple capillary test for ketones should be considered in unwell children younger than 10 years who present with vomiting or lethargy, as this may identify the need for specific therapy to resolve ketosis.

A patient with glycogen storage disease type 0 and a novel sequence variant in GYS2: a case report and literature review

Glycogen storage disease type 0 (GSD0) is an autosomal recessive disorder caused by a sequence variant in the GYS2 gene, leading to decreased or absent activity of hepatic glycogen synthase. With a frequency of less than 1 in 1,000,000 individuals, GSD0 represents only around 1% of all glycogen storage disease cases but it might be underrecognized. A 13-month-old girl of reportedly unrelated parents presented with a decreased level of consciousness, twitching in her left cheek, and munching. During a fasting test, hyperketotic hypoglycemia was found. A novel homozygous GYS2 gene sequence variant p.Thr445Arg was later confirmed by next-generation gene sequencing. After establishing a cornstarch- and protein-rich diet, the hypoglycemic episodes subsided and the patient’s neurocognitive development was normal. To date, only 39 patients with 24 disease-causing gene variants have been identified in GSD0, and we review their characteristics. Because of the heterogeneous phenotypes, GSD0 is an underdiagnosed disorder. In patients with hyperketotic hypoglycemia and postprandial hyperglycemia, GYS2 gene analysis should be performed.

Towards enhanced understanding of idiopathic ketotic hypoglycemia: a literature review and introduction of the patient organization, Ketotic Hypoglycemia International

BACKGROUND

Idiopathic Ketotic hypoglycemia (IKH) is a diagnosis of exclusion. Although considered as the most frequent cause of hypoglycemia in childhood, little progress has been made to advance the understanding of IKH since the medical term was coined in 1964. We aimed to review the literature on ketotic hypoglycemia (KH) and introduce a novel patient organization, Ketotic Hypoglycemia International (KHI).

RESULTS

IKH may be diagnosed after the exclusion of various metabolic and hormonal diseases with KH. Although often mild and self-limiting, more severe and long-lasting IKH occurs. We therefore divide IKH in physiological KH and pathological KH, the latter defined as recurrent symptomatic, or occasionally symptomatic, episodes with beta-hydroxybutyrate ≥ 1.0 mmol/L and blood glucose < 70 mg/dL (3.9 mol/L), in the absence of prolonged fasting, acute infections and chronic diseases known to cause KH. Pathological KH may represent undiscovered diseases, e.g. glycogen storage disease IXa, Silver-Russel syndrome, and ketone transporter defects, or suggested novel disease entities identified by exome sequencing. The management of KH aims to prevent hypoglycemia, fatty acid oxidation and protein deficiency by supplying adequate amounts of carbohydrates and protein, including nutritional therapy, uncooked cornstarch, and sometimes continuous tube feeding by night. Still, intravenous dextrose may be needed in acute KH episodes. Failure to acknowledge that IKH can be more than normal variation may lead to under-treatment. KHI is a non-profit, patient-centric, global organization established in 2020. The organization was created by adult IKH patients, patient family members, and volunteers. The mission of KHI is to enhance the understanding of IKH while advocating for patients, their families and the continued research into KH.

CONCLUSION

IKH is a heterogeneous disorder including physiological KH and pathological KH. IKH may represent missed diagnoses or novel disease entities, but shares common management principles to prevent fatty acid oxygenation. KHI, a novel patient organization, aims to enhance the understanding of IKH by supporting IKH families and research into IKH.