E-Poster Presentation ESA-SRB-ANZBMS 2021

A 39-year-old male was referred for evaluation of a 8 x 7.3 x 7.6cm left adrenal cystic mass in the context of hypertension. He was diagnosed with hypertension at age 33 years and experienced poor control despite four antihypertensive medications (perindopril 10mg daily, lercanidipine 20mg daily, moxonidine 400mcg daily and prazosin 0.5mg daily). He also had hypokalaemia, obstructive sleep apnoea and obesity. On initial assessment, his blood pressure (BP) was 175/100mmHg. There were no signs of cortisol excess. His initial biochemistry showed a potassium level of 3.2mmol/L with normal renal function. To assess the functionality of the left adrenal cystic mass, he had a 1mg dexamethasone suppression test, 24-hour urine free cortisol measurement and plasma metanephrines which were normal. To facilitate testing for aldosterone excess, perindopril and lercanidipine were changed to hydralazine 50mg BD and verapamil SR 180mg daily while prazosin and moxonidine were continued. Supplementation with 2400mg of potassium chloride per day was required to achieve normokalaemia. Plasma aldosterone-renin-ratio (ARR) was measured twice: the first was 88 (aldosterone 1140pmol/L, renin 13mIU/L) while the second was 268 (aldosterone 1070pmol/L, renin 4mIU/L) with a serum potassium of 3.6mmol/L and eGFR >90mL/min. Saline suppression test was bypassed. He underwent adrenal vein sampling (AVS) which demonstrated clear-cut right-sided lateralization with a lateralization index of 8.6 and contralateral suppression prior to ACTH stimulation. However, the right-sided lateralization was blunted following ACTH stimulation with lateralization index falling to 2.6 and loss of contralateral suppression. A right adrenalectomy was performed. Histopathology showed a 10mm cortical adenoma. Immuno-histochemistry showed absence of CYP11B2 staining within the adenoma but presence of aldosterone-producing cell clusters outside the adenoma (Figure 1). Four months post-surgery, he only required two antihypertensive medications to control his BP at <140/90mmHg, however biochemical cure is yet to be achieved (ARR 165, aldosterone 610pmol/L, renin 3.7mU/L).