Endocrine Abstracts

Case history: A 39-year-old gentleman was referred to the Endocrine clinic with a 5-year history of hypertension and intermittent hypokalaemia. He had been seen in the hypertension clinic, screened for secondary causes, and found to have an aldosterone of 604 pmol/l, renin <0.2 nmol/l/hr and potassium 3.7 mmo/l (off interfering medication), in-keeping with a diagnosis of Primary Aldosteronism (PA). His blood pressure was 126/82 mmHg on Ramipril 10 mg, Amlodipine 5 mg OD and Spironolactone 25 mg OD. There was no family history of hypertension and on examination he had long-standing vitiligo. Although initially preferring indefinite medical therapy to surgery, he subsequently enquired about less invasive options than total adrenalectomy. He met the eligibility criteria for the FABULAS trial (Feasibility study of RadioFrequency endoscopic Ablation with Ultrasound guidance as a non-surgical, Adrenal Sparing treatment for aldosterone-producing adenomas).

Investigations: Prior to radiofrequency ablation (RFA), [¹¹C]-metomidate PET-CT (MTO) was performed to confirm that the nodule on CT was the sole site of aldosterone production. A post-ablation MTO was performed to assess radiographic response to treatment.

Results and treatment: CT adrenal demonstrated a left adrenal lesion with HU<0 and no contralateral nodules. The pre-ablation MTO demonstrated: a 22 × 17 mm nodule, TOF SUVmax right 9.7 and left 18.6, to give a ratio of 1.92 (>1.25 confirms lateralisation). Prior to ablation, he was alpha- and beta-blocked (with doxazosin and bisoprolol) for 2 weeks, in case of peri-procedural adrenomedullary excitation. In a 10-minute procedure under deep sedation, the tumour was viewed under endoscopic ultrasound guidance and ablated at 8 places using a 10 mm Starmed RFA probe at 30 W. There were no haemodynamic changes during the RFA, and no abnormalities on the post-RFA safety CT. The patient was able to resume normal activities the next day, and all antihypertensives were stopped post-procedure. 6-month post-ablation results: aldosterone 131 pmol/l, renin 0.2 nmol/hr and potassium 4.7 mmol/l. PET CT demonstrated: a mainly cold, shrunken 21 × 12 mm nodule on CT, SUVmax right 13.3, left 12.2 to give a ratio of 0.92 vs the contralateral adrenal. His blood pressure is now 116/72 mmHg off medication.

Conclusions and points for discussion: This case, and others in FABULAS, provide proof-of-concept for a short, minimally-invasive procedure to replace adrenalectomy on the left side as a complete cure for PA. Multiple short-distance burns visualised in real-time render endoscopic RFA safe and potentially effective. It is now being compared with surgery in a randomised controlled trial (WAVE).