Pituitary Disorders USMLE Step 1 Practice Question
A 68-year-old man with a history of pituitary surgery 10 years ago presents with progressive fatigue and generalized weakness. Vital signs show BP 105/68 mmHg, HR 82/min, RR 16/min, temperature 36.8°C. Laboratory studies reveal sodium 128 mEq/L, morning cortisol 3 μg/dL (normal 10-20 μg/dL), and ACTH 15 pg/mL (inappropriately normal). TSH is normal. Which of the following is the most likely diagnosis?
Answer choices
- ASyndrome of inappropriate antidiuretic hormone secretion
- BAcute adrenal crisis from pituitary metastasis
- CCentral adrenal insufficiencyCorrect answer
- DHypothyroidism
- EPrimary adrenal insufficiency
- FSecondary hypothyroidism with concurrent hyponatremia from thyroid hormone replacement
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