A 40-year-old man comes to the physician because of weight gain over the past 3 months. During this period, he has gained 10 kg (22 lb) unintentionally. He also reports decreased sexual desire, oily skin, and sleeping difficulties. There is no personal or family history of serious illness. The patient appears lethargic. His temperature is 37°C (98.6°F), pulse is 80/min, and blood pressure is 150/90 mm Hg. Physical examination shows central obesity, acne, and thin, easily bruisable skin with stretch marks on the abdomen. Fasting plasma glucose level is 135 mg/dL and 24-hour urinary cortisol is increased. Further evaluation reveals that high-dose, but not low-dose, dexamethasone suppresses serum cortisol levels. Serum ACTH levels are high-normal. Which of the following is the most likely cause of this patient's symptoms?

Question

A 40-year-old man comes to the physician because of weight gain over the past 3 months. During this period, he has gained 10 kg (22 lb) unintentionally. He also reports decreased sexual desire, oily skin, and sleeping difficulties. There is no personal or family history of serious illness. The patient appears lethargic. His temperature is 37°C (98.6°F), pulse is 80/min, and blood pressure is 150/90 mm Hg. Physical examination shows central obesity, acne, and thin, easily bruisable skin with stretch marks on the abdomen. Fasting plasma glucose level is 135 mg/dL and 24-hour urinary cortisol is increased.  Further evaluation reveals that high-dose, but not low-dose, dexamethasone suppresses serum cortisol levels.  Serum ACTH levels are high-normal.  Which of the following is the most likely cause of this patient's symptoms?

Quizplus · Accepted Answer

Eductional Objective: In Cushing syndrome due to an ACTH-secreting pituitary adenoma (Cushing disease), ACTH is high and cortisol production can be suppressed by high-dose, but not low-dose, dexamethasone.  In patients with ectopic ACTH production (eg, from malignant tumors), cortisol and ACTH production are not suppressed by low- or high-dose dexamethasone.

A 40-Year-Old Man Comes to the Physician Because of Weight