Endocrine Abstracts

A 39 year-old man was referred with resistant hypertension from the nephrology service. Diagnosis was at 26 years and associated with hypokalaemia, left ventricular hypertrophy and proteinuria. Initial results (on amiloride) were: Aldosterone (A) 1900 pmol/l, direct renin (R) 10.2mU/mL and Aldosterone:Renin Ratio (ARR) 186. Saline suppression testing off interfering medications confirmed primary aldosteronism (PA): Aldosterone 1050 pmol/l, Renin 4.1uIU/mL and ARR 256 at four hours. Adrenal CT demonstrated bilateral adrenal abnormalities including right-sided (21mm) and left-sided (12mm) lesions. Adrenal vein sampling was suboptimal with incomplete cannulation of the right adrenal vein, but showed suppression on the left [Aldo/Cortisol (A/C) ratios: inferior vena cava 6.1 and left adrenal vein 0.9]. He was initially managed with four agents at high doses, including spironolactone. After MDM discussions, C¹¹-metomidate PET scan was performed. This demonstrated bilateral focal uptake, albeit with the highest uptake in the 21mm right sided nodule with an SUV max ratio of 1.44:1 compared to the left adrenal nodule. After counselling, the patient underwent right laparoscopic adrenalectomy for disease control rather than with curative intent. Surgery was complicated by transient mild hypotension and acute kidney injury. Four weeks later biochemistry had normalised (A 294 pmol/l, R 16.0 mU/ml, ARR18). At eight weeks postoperatively, he required two anti-hypertensives at lower doses with BP 127/85. He therefore currently demonstrates complete biochemical cure and partial clinical cure (PASO criteria). However close surveillance is planned given the potential for the unmasking of left-sided disease. This is the first patient at our Regional Centre where C11-metomidate PET scanning was used to investigate PA with bilateral lesions. Molecular imaging may, in the future, replace rather than supplement dynamic testing in these complex cases and may open the door to selective nodule ablation or debulking surgery in bilateral disease.