Endocrine Abstracts

Introduction: Clinical Practice Guidelines¹ advocate adrenal vein sampling (AVS) to distinguish between unilateral and bilateral primary aldosteronism (PA). Cannulating the right adrenal vein is difficult, and there is a lack of standardisation in sampling procedure and interpretation². We audited our local service to identify improvements.

Methods: All AVS procedures performed between January 2018-December 2020 (n = 31) were reviewed. Data on screening using aldosterone:renin ratios (ARR), saline infusion confirmatory testing, imaging, AVS results and treatment decisions were reviewed against local and literature criteria^1-2.

Results: Elevated ARR (>30pmol/mU) was the indication for AVS in 19 patients. 9/19 had persistent hypokalaemia (< 3.5 mmol/l). A positive (>280pmol/l), intermediate (191–280pmol/l) and negative (< 140pmol/l) aldosterone result post-saline infusion was observed in 47.4, 15.8 and 5.3% of patients, respectively. 31.6% had no confirmatory testing data. One patient declined AVS, and the remainder had sequential sampling for cortisol and aldosterone without ACTH stimulation. 25 PA-AVS procedures were performed (6/19 patients had repeat sampling). A selectivity index of >3:1, >2:1, and < 2:1 defined successful, probable and failed catheterisation²; 40% PA-AVS procedures were successful, 40% probably successful and 20% failed. A lateralisation index of >2:1 was considered significant² with contralateral suppression providing additional assurance. Successful catheterisation and concordance between biochemistry, imaging and treatment decisions was achieved in 27.8% of PA-AVS patients. PET-CT Metomidate was a useful adjunct for treatment decisions in 27.8% patients with either failed or unclear AVS results. Otherwise, treatment decisions were based on imaging/clinical factors alone. Treatment involved adrenalectomy in 57.9% of patients (3 right, 8 left) and medical management in the remaining 42.1% (2 may be surgical candidates).

Conclusions: Difficulties in catheterisation and complexities in interpreting results limit the utility of AVS in reliably informing PA treatment decisions. Improvements in biochemical reporting may help. Emerging tests like Metomidate scans and steroid profiling warrant further investigation³.