Endocrine Abstracts

Case History: In 2011, an asymptomatic 63-year-old professor was found to have isolated hypokalemia. He was normotensive and his only past medical history was hypercholesterolaemia. Investigations were suggestive of Primary Hyperaldosteronism (PHA): aldosterone 1055 pmol/L, renin mass 10 mU/L, Na⁺137 mmol/L, K⁺3.2 mmol/L, bicarbonate 31 mmol/L. A CT scan was reported as normal, but a 12mm nodule was subsequently noted contiguous with the left adrenal. A metomidate PET CT showed high uptake in this nodule, and likely a unilateral cause of PHA.

Results and treatment: His hypokalaemia was controlled by amiloride, but over the next few years he became progressively more hypertensive, and plasma renin was suppressed. In 2017 he developed palpitations, associated with dyspnoea and occasional dizziness. A Kadir device fitted by the cardiologists confirmed a diagnosis of paroxysmal atrial fibrillation (pAF). Echocardiogram was essentially normal, including the size of the left atria. The incidence of pAF is 7-12 fold higher among patients with PHA than with essential hypertension. However he was not keen to undergo adrenalectomy. In 2018, he enrolled in a feasibility study of endoscopic ultrasound-guided radiofrequency ablation of left-sided aldosterone producing adenomas (APA). 3 months post ablation his biochemistry (on Amiloride 10 mg) is as follow: aldosterone 5020 pmol/L, renin 2.37 ng/l, bicarbonate 30 mmol/L, K⁺4.2 mmol/L. Reassuringly there has been a significant reduction in the number of symptomatic pAF episodes he is now experiencing. He reports only 2 episodes in the 3 months post-procedure, compared weekly episodes pre-procedure. A repeat metomidate PET CT is awaited, to ascertain whether there is evidence of improvement on radiology.

Points for discussion: We present an unusual case of PHA where hypokalaemia (without hypertension) was the predominant feature for many years. The unconventional management plan was driven by the patient’s limited disease burden from his hypertension (he only required one antihypertensive medication), and his aversion to surgery. Ablation of APAs have been successfully performed via percutaneous and retroperitoneal approaches, usually for patients unfit for surgery. This is the first case where an endoscopic approach has been used. Its safety and efficacy is currently being assessed via the FABULAS Study; and has the potential to revolutionise the future management of PHA. This minimally invasive procedure has a significantly shorter recovery time compared to laparoscopic adrenalectomy. More excitingly, it could potentially open the door to offer definitive treatment for patients with bilateral disease: by surgical removal of the right adrenal and endoscopic RFA of left sided APAs.