Case presentation
We reported a 5-month-old boy with median cleft lip and palate, with several episodes of myoclonic seizure and profound persisted hypernatremia. Magnetic resonance (MRI) revealed the septum pellucidum was absent and HPE was reported. During laboratory investigation, his primary sodium level was 170 mmol/L and his urine specific gravity was 1003. based on these findings and clinical response to vasopressin, diagnosis of central diabetes insipidus was made.