A 55-year-old man 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.A chest x-ray reveals a hilar mass with adenopathy on the left side. Which of the following additional laboratory abnormalities are most likely to be present in this patient?

Question

A 55-year-old man 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.A chest x-ray reveals a hilar mass with adenopathy on the left side.  Which of the following additional laboratory abnormalities are most likely to be present in this patient?

Quizplus · Accepted Answer

Eductional Objective: Ectopic production of antidiuretic hormone (ADH) from malignancy can lead to the syndrome of inappropriate ADH secretion, a condition of impaired urinary water excretion.  This condition manifests with low serum osmolality, hyponatremia, high urine osmolality, and high urine sodium.

A 55-Year-Old Man Is Brought to the Emergency Department by a Friend