Vincristine-induced acute life-threatening hyponatremia resulting in seizure and coma

We report a case of a four-year-old boy with stage 1 Wilms tumour, who developed Vincristine-induced acute life- threatening hyponatremia, which presented as generalized tonic clonic seizures and coma. He was intubated and mechanically ventilated. There were no localizing neurological signs. CSF study showed no cells and CSF proteins were 20 mg%. Electrocardiography, chest X-ray, echocardiography, CT scan and liver function tests were normal. Evaluation of electrolytes and arterial blood gas showed serum sodium of 113 mEq/L with mild metabolic acidosis. Serum osmolality was 260 mOsm/L (normal value 285-295 mOsm/L) and urine osmolality was 625 mOsm/L (normal range 300-900 mOsm/L), urine sodium 280 mEq/d (normal range 100-260 mEq/d), serum potassium, blood urea, blood sugars were normal. Serial blood cultures showed no bacterial growth. Patient was treated with fluid restriction, hypertonic saline (3%) and other supportive care. Patient improved clinically over three days and was extubated on the third day and shifted to the ward on the fifth day.