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Pathology 29

A 54-year-old woman is brought to the emergency department by ambulance with symptoms of fatigue, dizziness, and confusion. Her friend reports these symptoms have been present for the past 2 days. She has a history of major depressive disorder, hypertension, and recurrent urinary tract infection. She takes fluoxetine and lisinorpil Vital signs are within normal limits. Physical examination reveals that the patient is oriented only to self. The patient is found to have hyponatremia with a serum sodium level of 122 mEq/L and normal renal function. Urine sodium is 50 mEq/L and urine osmolality is 390 mosmol/kg.

Which of the following is the most likely cause of this patient's hyponatremia?

  • A) Adrenal insufficiency
  • B) Heart failure
  • C) Primary polydipsia
  • D) Renal tubular acidosis
  • E) Syndrome of inappropriate antidiuretic hormone secretion (SIADH)


Dr. Ted O'Connell


Dr. Ted O'Connell