Hyperinsulinemic Hypoglycemia in a Neonate

A 25-day-old girl born from consanguineous parents presented with seizures. She was apyretic, and, except for axial hypotonia, her neurological examination was normal. A cerebral scan and cardiac and abdominal ultrasonography did not detect any abnormality. First-line biological investigations showed hypoketotic hyperinsulinemic hypoglycemia [glucose, 1 mmol/L (18 mg/dL); reference, 4–6 mmol/L (70–110 mg/dL); insulin, 19.32 mUI/L; reference, 2.00–12.00 mUI/L] and a constant hyperlactatemia (5.7 mmol/L; reference, 0.5–2.2 mmol/L). Cortisol (258 nmol/L; reference, 250–800 nmol/L), ammonia (34 μmol/L; reference, <35), bicarbonate (21 mmol/L; reference, 22–30 mmol/L), and free fatty acids (459 μmol/L; reference, 250–800 μmol/L) were within the normal intervals. The inappropriate insulin secretion, along with postprandial hypoglycemia in a patient of consanguineous parents, suggested congenital hyperinsulinemic hypoglycemia. Thus, complementary investigations were performed, including a plasma acylcarnitine profile and urine organic acid analysis using GC-MS. Postprandial hypoglycemia usually results from an alteration of insulin secretion by the pancreatic β cells. Several rare diseases may trigger insulin secretion by disrupting mitochondrial energy metabolism regulation underlying insulin release such as deficiencies in sulfonylurea receptor 1, inward-rectifier potassium channels, …