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 mEq/L and osmolality is 270 mOsm/kg. She has no symptoms and is euvolemic on clinical examination. Urine sodium is 40 mEq/L and urine osmolality is 450 mOsm/kg.For the above patient with hyponatremia, select the most likely diagnosis.
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.
congestive heart failure (CHF)
extrarenal sodium and fluid losses
SIADH
polydipsia
Oncology