A 63-year-old woman was incidentally found to have a 3-cm right adrenal mass on a CT scan of abdomen during investigation for abdominal pain. Her medical history included angina, hypertension and hypercholesterolaemia. She was taking oestrogen-containing hormone replacement therapy, atenolol, bendroflumethiazide, simvastatin and aspirin.
On examination, her pulse was 60 beats per minute and regular, and her blood pressure was 150/90 mmHg. She was obese with a body mass index of 34 kg/m2 (18C25). Fundoscopy revealed grade II hypertensive retinopathy.
Investigations:
serum sodium137 mmol/L (137C144)
serum potassium3.0 mmol/L (3.5C4.9)
serum creatinine100 µmol/L (60C110)
plasma renin activity (after 30 min supine)0.4 pmol/mL/h (1.1C2.7)
plasma aldosterone (after 30 min supine)200 pmol/L (135C400)
overnight dexamethasone suppression test (after 1 mg dexamethasone):
serum cortisol75 nmol/L (<50)
24-h urinary free cortisol140 nmol (55C250)
24-h urinary metanephrine<1 µmol (<2)
24-h urinary normetanephrine1 µmol (<3)
What is the most likely cause of the hypertension?
A . Conn’s syndrome
B . Cushing’s syndrome
C . essential hypertension
D . phaeochromocytoma
E . renovascular disease
Answer: C
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