A 60 year old male presented with skin hyperpigmentation, central obesity, violet striae & proximal myopathy. His BP is 160/90 mmHg. Lab studies show hypokalemic metabolic alkalosis. Which of the following statements is true regarding this condition?: (A) Basal ACTH level is likely to be low., (B) Circulating coicotropin-releasing hormone is likely to be elevated., (C) Pituitary magnetic resonance imaging (MRI) will visualize all ACTH-secreting tumors., (D) Serum potassium level <3.3 mmol/L is suggestive of ectopic ACTH production
Answer is D. The given scenario suggests the diagnosis of Cushing syndrome. Basal ACTH levels are elevated in pituitary tumors & ectopic ACTH secretion Coicotropin-releasing hormone is rarely the cause of Cushing syndrome. MRI of the pituitary gland will not visualize lesions <2 mm Serum potassium level <3.3 mmol/L is suggestive of ectopic ACTH production Also, hypeension, hypokalemic metabolic alkalosis & glucose intolerance are more prominent in ectopic ACTH secretion than in pituitary tumors