A 50-year-old man with Cushing's disease (ACTH-dependent hypercortisolism from a pituitary microadenoma) undergoes successful trans-sphenoidal resection. Post-operatively, serum cortisol falls to 1.2 µg/dL on day 3. What does this low cortisol indicate and how should it be managed?
- A Adrenal crisis; requires permanent corticosteroid replacement with no expectation of recovery
- B Successful resection with suppression of the HPA axis; start hydrocortisone and taper gradually over 6–24 months as HPA axis recovers ✓
- C Residual disease; plan immediate re-operation
- D Normal post-operative finding requiring no intervention
Correct answer: B. Successful resection with suppression of the HPA axis; start hydrocortisone and taper gradually over 6–24 months as HPA axis recovers
Explanation
Post-operative hypocortisolism after curative pituitary surgery for Cushing's disease indicates successful resection — the normal corticotrophs suppressed by chronic hypercortisolism require months to recover. Hydrocortisone replacement is started and tapered gradually; most patients recover HPA axis function within 6–24 months. Permanent replacement is only needed if recovery does not occur.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.