Cisplatin-induced acute hyponatremia leading to a seizure and coma: a case report

We report a rare case of cisplatin-induced acute hyponatremia leading to a seizure and coma. A 66-year-old woman with breast cancer received adjuvant chemotherapy with docetaxel and cisplatin. She had no nausea, vomiting, or diarrhea during or after chemotherapy administration. She had an acute onset of a generalized seizure and coma on the fourth day after chemotherapy. On arrival in the emergency department, she was unconscious with a Glasgow Coma Score of 6 (eyes 1, verbal 1, motor 4). Computed tomography of the brain did not show any lesions. She had no underlying diseases except breast cancer. The laboratory studies showed severe hyponatremia (Na 113 mmol/L) with low plasma osmolality, and elevation of both urinary sodium and urinary osmolality. In addition, polyuria (about 4 L/day) was also noted. Her consciousness level gradually improved the next day with a rise in serum sodium after 3% NaCl infusion. She recovered fully with no sequelae. Assessment using the Naranjo probability scale suggested that cisplatin was the probable cause for the adverse event. The mechanism of hyponatremia induced by cisplatin in our case was thought to be renal salt wasting syndrome (RSWS). In conclusion, cisplatin-induced acute hyponatremia leading to seizures and coma is seen rarely. When RSWS is suspected, hypertonic saline should be administered.