Syndrome of inappropriate secretion of anti-diuretic hormone due to hypothalamic hamartoma: use of tolvaptan.

OBJECTIVES: Hypothalamic hamartoma (HH) typically presents with gonadotrophin-dependent precocious puberty and/or seizures. Other endocrine disturbances are rare. We describe an infant with syndrome of inappropriate secretion of anti-diuretic hormone (SIADH) and a HH. CASE PRESENTATION: A 6-week-old infant presented with seizures and life-threatening hyponatremia. A HH was identified on magnetic resonance imaging. Clinical examination and biochemistry were consistent with SIADH, and serum copeptin was high during hyponatremia, further supporting this diagnosis. Tolvaptan was effective in normalizing plasma sodium and enabling liberalization of fluids to ensure sufficient nutritional intake and weight gain and manage hunger. CONCLUSIONS: Hyponatremia due to SIADH is novel at presentation of a HH, and can be challenging to diagnose and manage. Successful management of hyponatremia in this case was achieved using tolvaptan.

Explainable Machine Learning for Real-Time Hypoglycemia and Hyperglycemia Prediction and Personalized Control Recommendations.

BACKGROUND: The occurrences of acute complications arising from hypoglycemia and hyperglycemia peak as young adults with type 1 diabetes (T1D) take control of their own care. Continuous glucose monitoring (CGM) devices provide real-time glucose readings enabling users to manage their control proactively. Machine learning algorithms can use CGM data to make ahead-of-time risk predictions and provide insight into an individual's longer term control. METHODS: We introduce explainable machine learning to make predictions of hypoglycemia (<70 mg/dL) and hyperglycemia (>270 mg/dL) up to 60 minutes ahead of time. We train our models using CGM data from 153 people living with T1D in the CITY (CGM Intervention in Teens and Young Adults With Type 1 Diabetes)survey totaling more than 28 000 days of usage, which we summarize into (short-term, medium-term, and long-term) glucose control features along with demographic information. We use machine learning explanations (SHAP [SHapley Additive exPlanations]) to identify which features have been most important in predicting risk per user. RESULTS: Machine learning models (XGBoost) show excellent performance at predicting hypoglycemia (area under the receiver operating curve [AUROC]: 0.998, average precision: 0.953) and hyperglycemia (AUROC: 0.989, average precision: 0.931) in comparison with a baseline heuristic and logistic regression model. CONCLUSIONS: Maximizing model performance for glucose risk prediction and management is crucial to reduce the burden of alarm fatigue on CGM users. Machine learning enables more precise and timely predictions in comparison with baseline models. SHAP helps identify what about a CGM user's glucose control has led to predictions of risk which can be used to reduce their long-term risk of complications.

Case Histories.

Conditions related to abnormalities of calcium and bone metabolism are large in number and are characterised by hypocalcaemia, hypercalcaemia, primary and secondary osteoporosis, rickets resulting from both vitamin D and phosphate metabolism disorders, and a series of miscellaneous conditions. Included in this chapter is a series of cases drawn from our clinics and from colleagues who have presented these clinical problems at the recent Advanced Courses in Paediatric Bone and Calcium Metabolism run by the British Paediatric and Adolescent Bone group. This series of cases is not fully comprehensive but is designed to cover the major aspects of bone- and calcium-related disorders.

Clinical and molecular characterisation of hyperinsulinaemic hypoglycaemia in infants born small-for-gestational age.

OBJECTIVE: To characterise the phenotype and genotype of neonates born small-for-gestational age (SGA; birth weight <10th centile) who developed hyperinsulinaemic hypoglycaemia (HH). METHODS: Clinical information was prospectively collected on 27 SGA neonates with HH, followed by sequencing of KCNJ11 and ABCC8. RESULTS: There was no correlation between the maximum glucose requirement and serum insulin levels. Serum insulin level was undetectable in five infants (19%) during hypoglycaemia. Six infants (22%) required diazoxide treatment >6 months. Normoglycaemia on diazoxide <5 mg/kg/day was a safe predictor of resolved HH. Sequencing of KCNJ11/ABCC8 did not identify any mutations. CONCLUSIONS: Serum insulin levels during hypoglycaemia taken in isolation can miss the diagnosis of HH. SGA infants may continue to have hypofattyacidaemic hypoketotic HH beyond the first few weeks of life. Recognition and treatment of this group of patients are important and may have important implications for neurodevelopmental outcome of these patients.

Mutational analysis of the GYS2 gene in patients diagnosed with ketotic hypoglycaemia.

BACKGROUND: Ketotic hypoglycaemia is a common form of hypoglycaemia in childhood. Biochemically, patients present with fasting hypoglycaemia but with normal hormonal and metabolite profiles (low serum alanine levels in some patients). Glycogen Storage Disease Type 0 (GSD0) is an autosomal recessive disease due to mutations in the GYS2 gene. Patients with GSD0 also present with fasting ketotic hypoglycaemia. The frequency of GSD0 in patients presenting with ketotic hypoglycaemia is not known. OBJECTIVE: To understand the frequency of GSD0 in patients presenting with ketotic hypoglycaemia and to report a novel mutation in the GYS2 gene. SUBJECTS: The GYS2 gene was sequenced in 50 patients diagnosed with ketotic hypoglycaemia. METHODS: All exons (including exon and intron boundaries) of the GYS2 gene were sequenced following amplification of the coding region by polymerase chain reaction (PCR). RESULTS: No mutations in GYS2 were found in 49 patients. One patient had a novel homozygous mutation (c.1802T>G; p. Leu601X) in exon 14 of the GYS2 gene. We believe this is the 18th mutation reported so far. This mutation is predicted to lead to premature truncation of the glycogen synthase protein with no function. This patient presented with fasting ketotic hypoglycaemia associated with postprandial hyperglycaemia and elevated lactate level. CONCLUSIONS: GSD0 is relatively rare in patients presenting with ketotic hypoglycaemia and a normal biochemical profile. Sequencing of the GYS2 gene is more likely to be positive in patients with fasting ketotic hypoglycaemia and concomitant postprandial hyperglycaemia with hyperlactataemia.

The clinical problem of hyperinsulinemic hypoglycemia and resultant infantile spasms.

Hyperinsulinemic hypoglycemia (HH) is a cause of severe hypoglycemia in the newborn and infancy period and is associated with a high risk of neurologic handicap and epilepsy. Infantile spasms after exposure to HH is rare and has been described in only 1 previous report. We report the clinical, biochemical, and neurodevelopmental characteristics of 5 patients with neonatal-onset HH who subsequently developed infantile spasms. All 5 patients had neonatal-onset HH of varying severity and duration. These patients presented with the characteristic ictal pattern of spasms in clusters at a mean age of 6.6 months. Characteristic hypsarrhythmia was noted in only 3 of 5 patients. Structural abnormality was found in only 1 of 4 patients who underwent MRI of the brain. Infantile spasms responded to medical treatment in 3 patients, spasms in 1 patient were refractory to antiepileptic drugs, and treatment duration was insufficient for us to comment on the response in 1 patient. Developmental delay was evident in all of them. In conclusion neonatal HH of varying severity is associated with later (after a latent period) development of infantile spasms. The latent period before the onset of the spasms can be variable; hence, long-term neurodevelopmental follow-up (until 1 year of age) is necessary.

Congenital hyperinsulinism due to a compound heterozygous ABCC8 mutation with spontaneous resolution at eight weeks.

BACKGROUND: Recessive inactivating mutations in ABCC8 and KCNJ11 (which encode the two subunits of the adenosine triphosphate-sensitive potassium (KATP) channels in beta-cells) are the most common cause of medically unresponsive congenital hyperinsulinism (CHI) which requires a near-total pancreatectomy. METHODS/RESULTS: A patient born at term with marked macrosomia (5,900 g) presented at the age of 2 h with severe hyperinsulinaemic hypoglycaemia. He failed to respond to treatment with the KATP agonist, diazoxide. An (18F)DOPA-PET scan showed intense diffuse uptake of (18F)DOPA (consistent with diffuse disease) and genetic analysis of the ABCC8 gene confirmed a compound heterozygote missense ABCC8 mutation (R168C/S606T). However, unexpectedly in this patient the hyperinsulinaemic hypoglycaemia started to improve spontaneously at 7 weeks of age prior to planned pancreatic surgery. CONCLUSIONS: This is the first report of a patient with clinically severe autosomal-recessive diffuse CHI due to a compound heterozygous ABCC8 mutation that has resulted in spontaneous resolution at such an early age. Compound heterozygote ABCC8 mutations result in complex interactions, and it is possible that this interaction may modify the potential disease pathogenesis. It is important that physicians are aware of this unusual outcome in order to avoid unnecessary early pancreatic surgery with potential life-long implications.