Pituitary Disorders USMLE Step 1 Practice Question
A 68 year old man with a long smoking history is brought in for confusion and unsteady gait. Blood pressure is normal and mucous membranes are moist. Serum sodium is 118 mEq per L, serum osmolality is low, urine sodium is high, and urine osmolality is inappropriately elevated. Which of the following is the most likely diagnosis?
Answer choices
- APrimary polydipsia
- BSyndrome of inappropriate antidiuretic hormone secretionCorrect answer
- CAdrenal medullary tumor
- DCerebral salt wasting with hypovolemia
- ECentral diabetes insipidus
- FHypothyroidism causing euvolemic hyponatremia via non-osmotic ADH stimulation
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