ODP388 Hypernatremia in a Male Adolescent Leading to Diagnosis of Septo-optic Dysplasia

INTRODUCTION: Septo-optic dysplasia (SOD) is a rare, heterogeneous condition defined by any combination of optic nerve hypoplasia, midline radiologic abnormalities and pituitary hypoplasia. The majority of cases are sporadic, but a number of familial cases have been described. Mutations in genes such as HESX1, SOX2 and SOX3 have been identified. Typically, SOD is diagnosed in newborns and infants with a reported incidence of 1: 10,000 live births. The diagnosis can be made when two or more features of the classic triad are present. If familial, genetic testing can be obtained to confirm the diagnosis. CLINICAL CASE: A 17 year and 7-month-old male patient with a history of cerebral palsy, paraplegia and obesity was admitted for management of a right arm osteomyelitis. We were initially consulted for incidentally discovered pre-diabetes (HbA1c: 6.4%), likely secondary to unhealthy eating patterns (negative pancreatic antibodies). He was made NPO prior to surgery and subsequently developed hypernatremia (161 mmol/L), which was initially thought to be iatrogenic due to large volume of normal saline received. Despite discontinuation of normal saline and replacement of free water, hypernatremia persisted (159-172 mmol/L). He had an elevated serum osmolality (321 mOsm/kg) with a low urine osmolality (240 mOsm/kg) and low specific gravity (<1. 005). He was also polyuric (urine output 4.7 mL/kg/hr). With mentioned findings and a Copetin level of 2mol/L, a diagnosis of compensated central DI was established. He initially required a vasopressin drip in addition to slow replacement of free water in order to normalize his sodium level. After his sodium was stabilized, he was started on treatment with oral desmopressin. An MRI obtained was remarkable for small optic nerves and a small optic chiasm. Ophthalmology evaluation confirmed small, hypoplastic optic nerves. Constellation of findings were indicative of septo-optic dysplasia, presenting with central diabetes insipidus. Other than an IGF-1 on the low side (155 ng/L, z-score: -2.7), there was no evidence of additional pituitary hormone deficiencies. CONCLUSION: The presence of cerebral palsy and central diabetes insipidus generated suspicion of midbrain defects, which may be associated with SOD. SOD is typically diagnosed in the newborn period, but this case points to the possibility of a more delayed presentation and diagnosis. SOD is a rare, highly heterogeneous condition. Both the age of presentation and which pituitary hormone deficiencies are present are variable. With early diagnosis, hormonal deficiencies can be monitored and replaced as required. A high index of suspicion is essential if features of the classic triad are present, regardless of age of presentation. Presentation: No date and time listed