Neonatal hyperinsulinemic hypoglycemia with a pathogenic KCNJ11 variant – A case report

Introduction: Congenital hyperinsulinism (CHI) is the most common cause of persistent hypoglycemia in neonates. Prompt recognition and treatment are essential to prevent neurological damage. Mutations in genes regulating insulin secretion, especially KCNJ11, are frequently implicated.

Aim: To present the diagnostic and therapeutic approach in a neonate with persistent hypoglycemia and a confirmed pathogenic KCNJ11 variant.

Case Presentation: A female neonate, born at 38+1 weeks via cesarean section, was admitted within hours of birth due to hypoglycemia (blood glucose 1.0 mmol/L) and desaturation. Laboratory findings showed hyperinsulinemia (insulin 54.1 µU/mL, C-peptide 7.41 ng/mL), metabolic acidosis, and elevated LDH. Glucose and corticosteroid therapy were insufficient, prompting initiation of diazoxide and chlorothiazide, resulting in clinical improvement. Genetic testing revealed a likely pathogenic heterozygous variant c.901C>G in the KCNJ11 gene. The infant was discharged in stable condition with endocrinology follow-up.

Discussion: KCNJ11 mutations may cause both autosomal dominant and recessive forms of CHI. Genetic confirmation is crucial for diagnosis and guiding therapy. Diazoxide is the treatment of choice in responsive forms. Early diagnosis and targeted treatment can prevent severe outcomes.

Conclusion: In neonates with persistent hypoglycemia, early metabolic and genetic evaluation is essential. Identification of a KCNJ11 mutation enabled targeted therapy and favorable clinical outcome.

Dr. Svjetlana Mikulić is a pediatrician and PhD candidate at the University Clinical Hospital Mostar. She has significant experience in neonatal intensive care and general neonatology. Currently, she works at the Department of Pulmonology and Allergology, managing both respiratory and allergic pediatric patients. Her research focuses on neonatal endocrinology, pediatric pulmonology, perinatal outcomes, and rare congenital disorders. Dr. Mikulić is actively involved in clinical research and regularly presents at national and international pediatric conferences.