Endocrine Abstracts

Background: Hyperinsulinemic hypoglycaemia refers to inappropriate secretion of insulin in the presence of low plasma glucose levels. One day old male infant 3.6kg, born to non-consanguineous parents referred for symptomatic hypoglycaemia. APGAR score was 8/10 and 9/10 at 1 and 5 minutes. There was no history of gestational diabetes mellitus in the mother. General physical examination was unremarkable. Glycemic monitoring revealed persistent hypoglycemia with low plasma glucose 43 mg/dl and 14 mg/dl, Cortisol; 690 nmol/l (171–536). His TSH: 8.53 mIU/ml (1–39), Free T4: 2.32 ng/dl (0.93–1.7), GH: >10 ng/ml, Plasma Lactate: 2.1 mmol/L (0.5–2.2) were within normal and Urine ketones negative. He responded to 10% Dextrose Water and Dextrose fortified breast milk. His glucose infusion rate (GIR) was tapered and stopped on day 4. However, hypoglycemia recurred (RPG 11 mg/dl) and glucose infusion was restarted (GIR of 1 mg/kg/minute) to maintain euglycemia. Serum insulin was inappropriately elevated at 16 mIU/L corresponding with plasma glucose 39 mg/dl and Insulin-Glucose ratio 0.41 (NR <0.25). Post glucagon stimulation test glucose level was also low at 30 mg/dl. A final diagnosis of ‘Persistent Hyperinsulinemic hypoglycemia’ was made. He was evaluated with 18 F- DOPA PET/CT showed diffuse DOPA uptake in pancreas. Molecular genetic investigation revealed two heterozygous mutations (Asp854Asn and Arg1394cys) in the ABCC8 gene. He was commenced on Diazoxide 10 mg/kg/day in four divided doses (up to 30 mg/kg/day) with which he maintained euglycemia and successfully weaned off glucose infusion. He demonstrated appropriate fasting tolerance on Diazoxide before discharge and did not have any neurodevelopmental deficits.

Conclusion: This case highlights the importance of prompt diagnosis of persistent hypoglycaemia in neonates and prevent neurodevelopmental complications. Mutations in ABCC8 and KCNJ11, are the most common cause.