A lab pattern indicating a corticotropin-secreting pituitary adenoma would show which combination?

A lab pattern indicating a corticotropin-secreting pituitary adenoma would show which combination?

• A. High corticotropin and low cortisol levels
• B. Low corticotropin and high cortisol levels
• C. High corticotropin and high cortisol levels
• D. Low corticotropin and low cortisol levels

Answer: (C)

A corticotropin-secreting pituitary adenoma drives the pituitary to release excess ACTH, which in turn stimulates the adrenal cortex to produce more cortisol. Because the tumor is actively secreting ACTH, cortisol levels rise as a downstream effect, leading to elevated levels of both ACTH and cortisol. This is why the correct pattern is high ACTH with high cortisol. In contrast, an adrenal source of cortisol excess would usually suppress ACTH (high cortisol, low ACTH), and primary adrenal insufficiency would show high ACTH with low cortisol.

A corticotropin-secreting pituitary adenoma drives the pituitary to release excess ACTH, which in turn stimulates the adrenal cortex to produce more cortisol. Because the tumor is actively secreting ACTH, cortisol levels rise as a downstream effect, leading to elevated levels of both ACTH and cortisol. This is why the correct pattern is high ACTH with high cortisol. In contrast, an adrenal source of cortisol excess would usually suppress ACTH (high cortisol, low ACTH), and primary adrenal insufficiency would show high ACTH with low cortisol.