A rare case of sorafenib-induced severe hyponatremia.

Sorafenib is an anti-angiogenic tyrosine kinase inhibitor used to treat patients with renal cell cancer and advanced hepatocellular cancer. Common adverse effects of sorafenib are rash, diarrhea, nausea, and abnormal liver function test and hand-foot syndrome.Here, we present a case of a 90-year-old male who was prescribed sorafenib after being diagnosed with hepatocellular cancer. At 1 week after sorafenib initiation, he was admitted to the emergency room for an evaluation of weakness. The patient had hyponatremia, a common electrolyte abnormality seen in cancer patients. His hyponatremia improved when the sorafenib was stopped, suggesting that this was a rare case of hyponatremia induced by sorafenib.Although sorafenib is used in the treatment of hepatocellular cancer, it can cause life-threatening complication such as hyponatremia. Early identification of the cause of hyponatremia can prevent serious adverse event.