Adrenal Hormones and Feedback

A 38-year-old woman presents with progressive fatigue, weight loss, and hyperpigmentation over 3 months. On examination, she has generalized darkening of skin, particularly in palmar creases and buccal mucosa. Her BP is 95/60 mmHg. Laboratory findings show Na⁺ 128 mEq/L, K⁺ 5.8 mEq/L, and fasting glucose 65 mg/dL. A morning cortisol level is 2 µg/dL (normal >10 µg/dL). What is the most appropriate next step in management?

A 38-year-old woman from Delhi presents with progressive fatigue, weight loss of 8 kg over 3 months, and recurrent hypoglycaemic episodes. On examination, she has hyperpigmentation of the buccal mucosa and palmar creases, blood pressure 95/60 mmHg, and mild postural dizziness. Laboratory investigations show: sodium 128 mEq/L, potassium 5.8 mEq/L, fasting glucose 65 mg/dL, and ACTH 850 pg/mL (normal <50). A morning cortisol is 2.2 μg/dL (normal 10–20). The dexamethasone suppression test shows no suppression of cortisol. What is the primary pathophysiological defect?

A 52-year-old man from Mumbai presents with progressive hypertension (160/95 mmHg), central obesity, easy bruising, and proximal muscle weakness. He has been on long-term oral prednisolone 20 mg daily for rheumatoid arthritis for 5 years. Laboratory studies show: fasting glucose 185 mg/dL, potassium 3.2 mEq/L, morning cortisol 18 μg/dL, ACTH 8 pg/mL (normal 10–50). A low-dose dexamethasone suppression test (1 mg overnight) shows cortisol of 16 μg/dL (normal <1.8). What is the most appropriate interpretation of these findings?

Which of the following best describes the mechanism by which cortisol exerts negative feedback on the hypothalamic-pituitary-adrenal (HPA) axis?

A 52-year-old man with a 10-year history of hypertension is found on screening to have a left adrenal nodule (2.2 cm) on CT abdomen done for renal artery stenosis evaluation. His BP is 148/92 mmHg despite triple antihypertensive therapy. Laboratory investigations show: morning cortisol 18 µg/dL (normal 10–20), 24-hour urinary free cortisol 95 µg/24 h (normal <50), plasma ACTH 8 pg/mL (normal 10–50), and potassium 3.2 mEq/L. What is the most appropriate next step in management?