Introduction: Beckwith–Wiedemann syndrome (BWS) is a congenital overgrowth disorder associated with dysregulation of genes on chromosome 11p15.5. Infants with BWS can present with hyperinsulinemic hypoglycemia. There are also distinctive clinical features including macrosomia, macroglossia and visceromegaly that may raise suspicion of this diagnosis. Case: A preterm female infant of 30 weeks gestation with a birth weight of 1.87 kg (97th centile) had recurrent hypoglycemia in the neonatal period, requiring escalation to a maximum glucose infusion rate of 17.6 mg/kg/min. Hypoglycemia only resolved after starting intravenous glucagon infusion. Critical sampling during hypoglycemia revealed serum insulin 3.9 µU/mL (3–25 µU/mL), serum ketone 0.2 mmol/L, cortisol 3,053 nmol/L and growth hormone 16.2 ng/mL. These findings supported the diagnosis of non-ketotic hyperinsulinemic hypoglycemia. She was commenced on oral diazoxide with resolution of hypoglycemia and discontinuation of glucagon. Examination at birth revealed macroglossia, hepatomegaly and ballotable kidneys. An initial US abdomen at birth revealed bilateral enlarged kidneys but normal liver. An initial chromosomal study revealed karyotype 46, XX. Over time, additional clinical features became evident fulfilling the diagnostic criteria for BWS, that is, polyhydramnios, large for gestational age, transient hypoglycemia, hyperinsulinism, macroglossia, hemihypertrophy, facial nevi, bilateral ear creases, hepatomegaly and ballotable kidney. A repeat US abdomen surveillance at 4 months old revealed a heterogeneous liver mass with marked vascularity, prompting a diagnosis of hepatic hemangioma. She was commenced on oral propranolol, with reduction in the size and vascularity of the liver hemangioma and decline in alpha-fetoprotein levels. Conclusion The clinical features of BWS may not be recognizable in a preterm baby in early neonatal period. Careful clinical examination should be done in a baby with persistent hyperinsulinemic hypoglycemia for underlying syndromal causes. US surveillance should also be carried out due to increased risk of hepatoblastoma or liver hemangioma in BWS, as was seen in this case.
Infant, Newborn ; Infant ; Beckwith-Wiedemann Syndrome ; Infant, Premature ; Hypoglycemia

Introduction: Hypernatremia in preterm babies is often due to insensible water loss, inadequate fluid intake or sodium imbalance due to immature kidneys. Congenital nephrogenic diabetes insipidus (CNDI) is an uncommon cause of hypernatremia in neonates and presents shortly after birth. Early recognition is important to prevent severe dehydration, electrolytes imbalance and neurological complications. Case: We report a case of a preterm 32-week female infant, with a birth weight of 1.14 kg with persistent hypernatremia (146– 156 mmol/L) from day 4 of life. She received total parenteral nutrition since birth and was started on breastmilk since day 5 of life. The baby was mildly dehydrated with weight loss and high urea (6.5 mmol/L) at day 7 of life. Total fluids were increased to 160 mL/kg/day but serum sodium remained elevated even though the urea had normalized. The infant was also noted to have high urine output (5–6 mL/kg/hour) since day 3 of life and suboptimal weight gain. Further evaluation at age 1 month revealed urine osmolality 71 mOsm/kg, serum osmolality 308 mOsm/kg and urine sodium <20 mmol/L when serum sodium was 150 mmol/L, suggestive of DI. A trial of desmopressin showed unchanged serum sodium (Na), suggesting nephrogenic DI. Administration of intravenous fluids of 1/5NSD10% resulted in further increase of both sodium (159 mmol/L) and serum osmolality (326 mOsm/kg) with low urine osmolality (111 mOsm/kg). Intravenous fluids were discontinued and she was started on hydrochlorothiazide (1 mg/kg/dose bd), resulting in gradual normalization of sodium 138 mmol/L. Post discharge, she had good weight gain and normal developmental milestones at corrected age of 1.5-month-old. Due to early onset hypernatremia, the infant was referred for genetic testing to rule out CNDI. Conclusion Early onset persistent hypernatremia and high urine output despite adequate fluid management should prompt evaluation of DI. Early diagnosis is crucial to prevent a chronic state of hypernatremia that can lead to growth and developmental delay.
Infant, Newborn ; Dehydration ; Hypernatremia