ESPE Abstracts

Background: We present the case of an infant with congenital hyperinsulinism presenting with persisting hypoglycaemias.

Case Presentation: The boy was born at 37+3 weeks, weighing 4690g (>99. Percentile, Z-score +3.38). Large for gestational age status was suspected throughout pregnancy, gestational diabetes had been excluded via an oral glucose tolerance test twice. The newborn was initially treated at a secondary care centre presenting with recurrent severe hypoglycaemias (min. 23 mg/dl), necessitating continuous glucose infusion (up to 22g/kg/d) in the first week of life and subsequent maltodextrin enrichment of formula milk until the 28^th day. The suspicion of congenital hyperinsulinism was raised by repeated finding of high insulin levels (max 26.8 mU/l, norm <3 mU/l) and the diagnosis was confirmed at genetic testing with the finding of a paternally inherited heterozygous mutation in the KCNJ11 gene, encoding for the pore forming ATP-sensitive potassium (_KATP) channel. Diazoxide was initially started (up to 12.5 mg/kg/d), leading to normoglycaemia but the patient showed peripheral oedemas and beginning cardiac hypertrophy, necessitating hydrochlorothiazide and metoprolol treatment. The infant was discharged at 4 weeks. At follow-up, the patient showed recurrent hypoglycaemias and presented at our tertiary care centre at the age of 5 months. We placed a continuous glucose monitoring device. Data revealed recurrent hypoglycaemias (42% of time <60 mg/dl), so that we hospitalized the patient and started a subcutaneous octreotide therapy, starting with 10 µg doses up to 7,5 µg/kg/day in 3 doses, resulting in increasing glycaemic levels. However, the patient still showed occasional hypoglycaemias, so that we started a continuous subcutaneous infusion (CSI) with octreotide. Under continuous octreotide infusion of 18 µg/kg/day, the patient showed a normoglycaemic state. At follow up visit after 2 and 4 weeks, blood glucose levels were still stable.

Conclusion: Treatment of congenital hyperinsulinism is challenging, but the avoidance of hypoglycaemias is crucial for a normal brain development. First line therapy with diazoxide is effective only in a limited number of cases and often shows side effects. Off-label octreotide is a valid alternative, the administration via a CSI device offers the possibility to allow good hypoglycaemia control throughout the day. The next step will be an L-Dopa PET-CT examination to differentiate between focal and diffuse lesions.