A 55-year-old man with a seizure disorder is brought to the emergency department by a friend because of progressive confusion over the past two weeks. He is unable to provide any history. His vital signs are within normal limits. He appears lethargic and is only oriented to person. Oral mucosa is moist. There is no jugular venous distention. A basic metabolic panel shows a serum sodium concentration of 115 mEq/L but is otherwise normal. Which of the following is the most likely cause of this patient's hyponatremia?

Question

Quizplus · Accepted Answer

Eductional Objective: Hyponatremia following cerebral injury (eg, subarachnoid hemorrhage) is commonly due to the syndrome of inappropriate antidiuretic hormone secretion.  Injury to the hypothalamus leads to increased secretion of antidiuretic hormone, which in turn leads to water retention, low serum osmolality, and increased urinary sodium excretion.

A 55-Year-Old Man with a Seizure Disorder Is Brought to the Emergency