Dengue Encephalitis associated with symptomatic hyponatremia due to Syndrome of Inappropriate Antidiuretic Hormone Secretion.

A previously well 21-year-old girl presented to Hospital Teluk Intan, Perak, Malaysia with a short history of fever, vomiting and altered sensorium. She was diagnosed with dengue encephalitis as her dengue NS-1 antigen was positive and her cerebrospinal fluid (CSF) dengue polymerase chain reaction (PCR) was positive with serotype DENV-2. She also had severe hyponatremia due to Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) which caused an episode of seizure. She recovered well with supportive management. SIADH and dengue encephalitis should be considered as one of the differential diagnosis in patients presenting with fever and altered sensorium especially in dengue endemic countries like Malaysia.