NBME 21

nbme21/Block 4/Question#6

A 55-year-old man comes to the physician because of ...

Cortisol

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submitted by beeip(8),

This has been a tough concept for me to get, but I think I'm finally there:

The stem is describing primary adrenal insufficiency, or Addison's.

  • ACTH is being over-produced to stimulate the adrenals to produce cortisol, but they can't respond, either due to atrophy or destruction (TB, autoimmune: DR4, etc.)
  • The first 13 amino acids of ACTH can be cleaved to form α-MSH, which stimulates melanocytes, causing hyperpigmentation