<prompt> A 65-year-old woman is admitted to the hospital after a stroke resulting in left hemiparesis. She has no trouble swallowing and is on a full diet. One week later, on routine biochemistry, her sodium is 128 mEqL and osmolality is 270 mOsmkg. She has no symptoms and is euvolemic on clinical examination. Urine sodium is 40 mEqL and urine osmolality is 450 mOsmkg.For the above patient with hyponatremia, select the most likely diagnosis.congestive heart failure CHFextrarenal sodium and fluid lossesSIADHpolydipsia  <response>: SIADH is associated with many CNS diseases including meningitis, encephalitis, tumors, trauma, stroke, and acute porphyria. It is assumed that antidiuretic hormone ADH in these patients is secreted in response to direct stimulation of the hypothalamic osmoreceptors. 